Revert "powerpc/xmon: Relax frame size for clang"

This reverts commit 9c87156c.

I have not been able to reproduce the reported -Wframe-larger-than=
warning (or disassembly) with clang-11 or clang-18.

I don't know precisely when this was fixed in llvm, but it may be time
to revert this.

Closes: https://github.com/ClangBuiltLinux/linux/issues/252


Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230817-ppc_xmon-v1-1-8cc2d51b9995@google.com