gas: sframe: Use appropriate struct cfi_insn_data union members

gas: sframe: Use appropriate struct cfi_insn_data union members

Use the appropriate struct cfi_insn_data union members to access
fields when generating SFrame information from CFI directives.

gas/
	* gen-sframe.c (sframe_xlate_do_def_cfa, sframe_xlate_do_offset,
	sframe_xlate_do_val_offset): Access ri fields, as .cfi_def_cfa,
	.cfi_offset, and .cfi_val_offset define a register and offset
	value.
	* (sframe_xlate_do_def_cfa_register): Access r field, as
	.cfi_def_cfa_register defines a register.

Signed-off-by: Jens Remus <jremus@linux.ibm.com>