powerpc/64e: Convert cmpi to cmpwi in head_64.S

From 80f23935cadb ("powerpc: Convert cmp to cmpd in idle enter sequence"):

  PowerPC's "cmp" instruction has four operands. Normally people write
  "cmpw" or "cmpd" for the second cmp operand 0 or 1. But, frequently
  people forget, and write "cmp" with just three operands.

  With older binutils this is silently accepted as if this was "cmpw",
  while often "cmpd" is wanted. With newer binutils GAS will complain
  about this for 64-bit code. For 32-bit code it still silently assumes
  "cmpw" is what is meant.

In this case, cmpwi is called for, so this is just a build fix for
new toolchains.

Cc: stable@vger.kernel.org # v3.0+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/head_64.S

@@ -221,9 +221,9 @@ booting_thread_hwid:
  */
 _GLOBAL(book3e_start_thread)
 	LOAD_REG_IMMEDIATE(r5, MSR_KERNEL)
-	cmpi	0, r3, 0
+	cmpwi	r3, 0
 	beq	10f
-	cmpi	0, r3, 1
+	cmpwi	r3, 1
 	beq	11f
 	/* If the thread id is invalid, just exit. */
 	b	13f
@@ -248,9 +248,9 @@ _GLOBAL(book3e_start_thread)
  * r3 = the thread physical id
  */
 _GLOBAL(book3e_stop_thread)
-	cmpi	0, r3, 0
+	cmpwi	r3, 0
 	beq	10f
-	cmpi	0, r3, 1
+	cmpwi	r3, 1
 	beq	10f
 	/* If the thread id is invalid, just exit. */
 	b	13f