Fix CLANG build errors (#345)

# Preface

Please ensure you have read the [contribution
docs](https://github.com/microsoft/mu/blob/master/CONTRIBUTING.md) prior
to submitting the pull request. In particular,
[pull request
guidelines](https://github.com/microsoft/mu/blob/master/CONTRIBUTING.md#pull-request-best-practices).

## Description

When building with CLANG/CLANGPDB, the compiler will generate errors for
where the variable could be used without being initialized.

This change is added to mitigate such errors and pave way to build ARM
platforms on Windows system.

For each item, place an "x" in between `[` and `]` if true. Example:
`[x]`.
_(you can also check items in the GitHub UI)_

- [x] Impacts functionality?
- **Functionality** - Does the change ultimately impact how firmware
functions?
- Examples: Add a new library, publish a new PPI, update an algorithm,
...
- [ ] Impacts security?
- **Security** - Does the change have a direct security impact on an
application,
    flow, or firmware?
  - Examples: Crypto algorithm change, buffer overflow fix, parameter
    validation improvement, ...
- [ ] Breaking change?
- **Breaking change** - Will anyone consuming this change experience a
break
    in build or boot behavior?
- Examples: Add a new library class, move a module to a different repo,
call
    a function in a new library class in a pre-existing module, ...
- [ ] Includes tests?
  - **Tests** - Does the change include any explicit test code?
  - Examples: Unit tests, integration tests, robot tests, ...
- [ ] Includes documentation?
- **Documentation** - Does the change contain explicit documentation
additions
    outside direct code modifications (and comments)?
- Examples: Update readme file, add feature readme file, link to
documentation
    on an a separate Web page, ...

## How This Was Tested

This was tested on QEMU SBSA platform and verified bootable to UEFI
Shell.

## Integration Instructions

N/A

SetupDataPkg/ConfApp/SetupConf.c

@@ -474,7 +474,7 @@ ProcessSvdUsbInput (
   VOID
   )
 {
-  EFI_STATUS  Status;
+  EFI_STATUS  Status = EFI_NOT_FOUND;
   CHAR16      *FileName;
   CHAR8       *XmlString;
   UINTN       XmlStringSize;
@@ -641,7 +641,7 @@ CreateXmlStringFromCurrentSettings (
   CHAR8                  *EncodedBuffer = NULL;
   UINTN                  EncodedSize    = 0;
   VOID                   *Data          = NULL;
-  CHAR8                  *AsciiName;
+  CHAR8                  *AsciiName     = NULL;
   UINTN                  AsciiSize;
   UINTN                  i;
   UINTN                  NumPolicies;