* config/tc-mips.c (S_EX_*): New enum for my_getSmallExpression()

	* config/tc-mips.c (S_EX_*): New enum for my_getSmallExpression()
	return values.
	(mips_ip): Use the new return values instead of characters. Add
	support for %higher and %highest.
	(LP): Remove.
	(RP): Remove.
	(my_getSmallExpression): Make parsing case insensitive and more
	reliable. Add support for %higher and %highest. Further support	to
	parse %gprel and %neg is implemented but currently deactivated.