MSP430: Add 'd', 'e', 'f' and 'g' asm operand modifiers

MSP430: Add 'd', 'e', 'f' and 'g' asm operand modifiers

The new operand modifiers can be used to select odd-numbered bytes of a memory
reference or constant value.

gcc/ChangeLog:

	* config/msp430/msp430.c (msp430_print_operand): Update comment.
	Cast to long when printing values formatted as long.
	Support 'd', 'e', 'f' and 'g' modifiers.
	Extract operand value with a single operation for all modifiers.
	* doc/extend.texi (msp430Operandmodifiers): New.

gcc/testsuite/ChangeLog:

	* gcc.target/msp430/operand-modifiers.c: Extend test to handle new
	modifiers.
	* gcc.target/msp430/operand-modifiers-bad.c: New test.