metal : fix `ggml_metal_supports_op` for BF16 (#8021) #31

Job	Run time
server (ADDRESS, RelWithDebInfo)	6m 0s
server-windows	7m 27s
server (THREAD, RelWithDebInfo)	13m 38s
server (UNDEFINED, RelWithDebInfo)	9m 1s
server (Release)	2m 40s
	38m 46s

Provide feedback