MAINTAINERS: Update my company e-mail address

Following my recent transition from Imagination Technologies to the
reincarnated MIPS company update MAINTAINERS entries accordingly.

	binutils/
	* MAINTAINERS: Update my company e-mail address.

	gdb/
	* MAINTAINERS: Update my company e-mail address.

	sim/
	* MAINTAINERS: Update my company e-mail address.