powerpc/kvm: Fix unannotated intra-function call warning

objtool throws the following warning:
  arch/powerpc/kvm/booke.o: warning: objtool: kvmppc_fill_pt_regs+0x30:
  unannotated intra-function call

Fix the warning by setting the value of 'nip' using the _THIS_IP_ macro,
without using an assembly bl/mflr sequence to save the instruction
pointer.

Reported-by: kernel test robot <lkp@intel.com>
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230128124158.1066251-1-sv@linux.ibm.com

Author: sathvika-v

arch/powerpc/kvm/booke.c

@@ -912,16 +912,15 @@ static int kvmppc_handle_debug(struct kvm_vcpu *vcpu)
 
 static void kvmppc_fill_pt_regs(struct pt_regs *regs)
 {
-	ulong r1, ip, msr, lr;
+	ulong r1, msr, lr;
 
 	asm("mr %0, 1" : "=r"(r1));
 	asm("mflr %0" : "=r"(lr));
 	asm("mfmsr %0" : "=r"(msr));
-	asm("bl 1f; 1: mflr %0" : "=r"(ip));
 
 	memset(regs, 0, sizeof(*regs));
 	regs->gpr[1] = r1;
-	regs->nip = ip;
+	regs->nip = _THIS_IP_;
 	regs->msr = msr;
 	regs->link = lr;
 }