Simplify some uses of utohexstr.

As a side effect hex is printed lowercase instead of uppercase now.

llvm-svn: 144013
diff --git a/llvm/test/MC/ARM/neon-bitwise-encoding.s b/llvm/test/MC/ARM/neon-bitwise-encoding.s
index bcf647c..72d0256 100644
--- a/llvm/test/MC/ARM/neon-bitwise-encoding.s
+++ b/llvm/test/MC/ARM/neon-bitwise-encoding.s
@@ -33,8 +33,8 @@
 
 @ CHECK: vbic	d16, d17, d16           @ encoding: [0xb0,0x01,0x51,0xf2]
 @ CHECK: vbic	q8, q8, q9              @ encoding: [0xf2,0x01,0x50,0xf2]
-@ CHECK: vbic.i32	d16, #0xFF000000 @ encoding: [0x3f,0x07,0xc7,0xf3]
-@ CHECK: vbic.i32	q8, #0xFF000000 @ encoding: [0x7f,0x07,0xc7,0xf3]
+@ CHECK: vbic.i32	d16, #0xff000000 @ encoding: [0x3f,0x07,0xc7,0xf3]
+@ CHECK: vbic.i32	q8, #0xff000000 @ encoding: [0x7f,0x07,0xc7,0xf3]
 
 	vorn	d16, d17, d16
 	vorn	q8, q8, q9