Fix build breakage from commit 6ec2b2

Fix build breakage from commit 6ec2b2

I was notified by buildbot that my patch (commit 6ec2b2) has broken the build
on x86_64:

../../binutils-gdb/gdb/rs6000-tdep.c: In function int ppc_process_record_op31(gdbarch*, regcache*, CORE_ADDR, uint32_t):
../../binutils-gdb/gdb/rs6000-tdep.c:4705:50: error: cannot convert CORE_ADDR* {aka long unsigned int*} to ULONGEST* {aka long long unsigned int*} for argument 3 to register_status regcache_raw_read_unsigned(regcache*, int, ULONGEST*)
         tdep->ppc_gp0_regnum + PPC_RA (insn), &ea);
                                                  ^
../../binutils-gdb/gdb/rs6000-tdep.c:4718:50: error: cannot convert CORE_ADDR* {aka long unsigned int*} to ULONGEST* {aka long long unsigned int*} for argument 3 to register_status regcache_raw_read_unsigned(regcache*, int, ULONGEST*)
         tdep->ppc_gp0_regnum + PPC_RA (insn), &ea);
                                                  ^
The patch below should fix it.

gdb/ChangeLog:
2016-09-22  Edjunior Barbosa Machado  <emachado@linux.vnet.ibm.com>

	* rs6000-tdep.c (ppc_process_record_op31): Fix
	regcache_raw_read_unsigned call using the correct parameter type.