powerpc/32: fix build failure on book3e with KVM

Build failure was introduced by the commit identified below,
due to missed macro expension leading to wrong called function's name.

arch/powerpc/kernel/head_fsl_booke.o: In function `SystemCall':
arch/powerpc/kernel/head_fsl_booke.S:416: undefined reference to `kvmppc_handler_BOOKE_INTERRUPT_SYSCALL_SPRN_SRR1'
Makefile:1052: recipe for target 'vmlinux' failed

The called function should be kvmppc_handler_8_0x01B(). This patch fixes it.

Reported-by: Paul Mackerras <paulus@ozlabs.org>
Fixes: 1a4b739b ("powerpc/32: implement fast entry for syscalls on BOOKE")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>