Fixed misplaced parenthesis and tidied up shadow variables.

gas:
	* config/tc-arc.c (md_assemble): No need to replace s by s2, limm
	by limm2 or limm_p by limm2_p. In each case we can just remove
	shadow declaration and reuse existing declaration.

opcodes:
	* arc-opc-old.c (arc_opcodes): Correct parentheses change for
	"brgt%.n %B,%u,%d".