stm32f4: Fixes erase_mass command return error.

The final erase_mass command check is looking for the EOP (End of
OPeration) bit to be set. This bit is only set when the EOP interrupts
(EOPIE = 1) are enabled. We are not enabling those on the target so this
bit will never get set. As we are monitoring the BSY flag to make sure
the erase_mass operation is still ongoing and finished it is enough if
we just check the error flags.

src/target/stm32f4.c

@@ -56,7 +56,7 @@ static int stm32f4_flash_erase(struct target_flash *f, target_addr addr,
 static int stm32f4_flash_write(struct target_flash *f,
                                target_addr dest, const void *src, size_t len);
 
-/* Flash Program ad Erase Controller Register Map */
+/* Flash Program and Erase Controller Register Map */
 #define FPEC_BASE	0x40023C00
 #define FLASH_ACR	(FPEC_BASE+0x00)
 #define FLASH_KEYR	(FPEC_BASE+0x04)
@@ -503,11 +503,8 @@ static bool stm32f4_cmd_erase_mass(target *t, int argc, const char **argv)
 	tc_printf(t, "\n");
 
 	/* Check for error */
-	uint32_t sr = target_mem_read32(t, FLASH_SR);
-	if ((sr & SR_ERROR_MASK) || !(sr & SR_EOP))
-		return false;
-
-	return true;
+	const uint32_t result = target_mem_read32(t, FLASH_SR);
+	return !(result & SR_ERROR_MASK);
 }
 
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