powerpc/64e: Fix obtool warnings in exceptions-64e.S

Since commit aec0ba74 ("powerpc/64: Use -mprofile-kernel for big
endian ELFv2 kernels"), this file is checked by objtool. Fix warnings
such as:

  arch/powerpc/kernel/idle_64e.o: warning: objtool: .text+0x20: unannotated intra-function call
  arch/powerpc/kernel/exceptions-64e.o: warning: objtool: .text+0x218: unannotated intra-function call

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230622112451.735268-1-mpe@ellerman.id.au