sparc: support %dN and %qN syntax for FP registers.

sparc: support %dN and %qN syntax for FP registers.

The SPARC Refence Manual documents the %dN and %qN syntax to
refer to double and quad-precision floating-point registers,
respectively.  See OSA2015 Appendix C, Assembly Language Syntax,
C1.1 Register Names.

This patch adds support for these names to GAS.  This eases the
porting of software from Solaris to GNU/Linux, as these register
names have been supported by the Solaris linker for a long time
and many assembler require that support.

gas/ChangeLog:

2015-12-09  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* config/tc-sparc.c (sparc_ip): Support %dN and %qN notation for
	double and quad-precision floating-point registers.