kbuild: dummy-tools: make MPROFILE_KERNEL checks work on BE

Commit 2eab791f ("kbuild: dummy-tools: support MPROFILE_KERNEL
checks for ppc") added support for ppc64le's checks for
-mprofile-kernel.

Now, commit aec0ba74 ("powerpc/64: Use -mprofile-kernel for big
endian ELFv2 kernels") added support for -mprofile-kernel even on
big-endian ppc.

So lift the check in gcc-check-mprofile-kernel.sh to support big-endian too.

Fixes: aec0ba74 ("powerpc/64: Use -mprofile-kernel for big endian ELFv2 kernels")
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>