ld: don't use ia64 register name in expression of pr16322 test

"f1" is a register name on ia64, and hence gets warned upon when used
as expression value:

.../binutils/2.25/ld/testsuite/ld-elf/pr16322.s: Assembler messages:
.../binutils/2.25/ld/testsuite/ld-elf/pr16322.s:6: Warning: register value used as expression

Change the name (and "p1" at once, which is a register name too, albeit
not currently causing any immediate problem).

ld/testsuite/
2015-01-08  Jan Beulich <jbeulich@suse.com>

	* ld-elf/pr16322.s (p1): Rename to px1.
	(f1): Rename to fx1.

--- 2015-01-08/ld/testsuite/ld-elf/pr16322.s	2014-02-20 15:36:37.000000000 +0100
+++ 2015-01-08/ld/testsuite/ld-elf/pr16322.s	2015-01-08 12:53:04.000000000 +0100
@@ -1,6 +1,6 @@
-	.globl	p1
+	.globl	px1
 	.section	.data.rel.ro,"aw",%progbits
 	.p2align 5
-	.type	p1, %object
-p1:
-	.dc.a	f1
+	.type	px1, %object
+px1:
+	.dc.a	fx1