powerpc/kvm/book3s_32: Fix MTMSR_EERI macro

Commit b38c77d8

 moved the MTMSR_EERI macro from the KVM code to generic
ppc_asm.h code. However, while adding it in the headers for the ppc32 case,
it missed out to remove the former definition in the KVM code.

This patch fixes compilation on server type PPC32 targets with CONFIG_KVM
enabled.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>