readelf: MSP430: Fix incorrect usage of "msp430x" in function names

readelf: MSP430: Fix incorrect usage of "msp430x" in function names

The "X" in "MSP430X" indicates an extension to the original MSP430 ISA, but
these functions are generically used for all MSP430 ISAs, so the names should
not use the "X" suffix.

binutils/ChangeLog:

	* readelf.c (get_msp430x_section_type_name): Rename to ...
	(get_msp430_section_type_name): ... this.
	(get_section_type_name): Use get_msp430_section_type_name.
	(display_msp430x_attribute): Rename to ...
	(display_msp430_attribute): ... this.
	(process_arch_specific): Use display_msp430_attribute.