* mips-tdep.c (mips_convert_register_float_case_p)

	* mips-tdep.c (mips_convert_register_float_case_p)
	(mips_convert_register_gpreg_case_p): New functions.
	(mips_convert_register_p): Invoke new functions above.
	(mips_register_to_value): Add case for fetching value shorter
	than 64 bits from a 64-bit register.
	(mips_value_to_register): Add case for storing value shorter
	than 64 bits into a 64-bit register.