powerpc/trace: Account for -fpatchable-function-entry support by toolchain

powerpc/trace: Account for -fpatchable-function-entry support by toolchain

So far, we have relied on the fact that gcc supports both
-mprofile-kernel, as well as -fpatchable-function-entry, and clang
supports neither. Our Makefile only checks for CONFIG_MPROFILE_KERNEL to
decide which files to build. Clang has a feature request out [*] to
implement -fpatchable-function-entry, and is unlikely to support
-mprofile-kernel.

Update our Makefile checks so that we pick up the correct files to build
once clang picks up support for -fpatchable-function-entry.

[*] https://github.com/llvm/llvm-project/issues/57031

Signed-off-by: Naveen N Rao <naveen@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20241030070850.1361304-2-hbathini@linux.ibm.com