kselftest/arm64: Use preferred form for predicate load/stores

The preferred form of the str/ldr for predicate registers with an immediate
of zero is to omit the zero, and the clang built in assembler rejects the
zero immediate. Drop the immediate.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221117114130.687261-1-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

tools/testing/selftests/arm64/abi/syscall-abi-asm.S

@@ -153,7 +153,7 @@ do_syscall:
 	// Only set a non-zero FFR, test patterns must be zero since the
 	// syscall should clear it - this lets us handle FA64.
 	ldr	x2, =ffr_in
-	ldr	p0, [x2, #0]
+	ldr	p0, [x2]
 	ldr	x2, [x2, #0]
 	cbz	x2, 2f
 	wrffr	p0.b
@@ -298,7 +298,7 @@ do_syscall:
 	cbz	x2, 1f
 	ldr	x2, =ffr_out
 	rdffr	p0.b
-	str	p0, [x2, #0]
+	str	p0, [x2]
 1:
 
 	// Restore callee saved registers x19-x30