Remove {fetch,store}_fpregister and {fetch,store}_register

Remove {fetch,store}_fpregister and {fetch,store}_register

This patch is to remove fetch_fpregister, fech_register,
store_fpregister and store_register, and use fetch_fpregs,
fetch_regs, store_regs, and store_fpregs instead.

gdb:

2015-07-07  Yao Qi  <yao.qi@linaro.org>

	* arm-linux-nat.c (store_fpregister): Remove.
	(store_register): Likewise.
	(fetch_fpregister): Likewise.
	(fetch_register): Likewise.
	(arm_linux_store_inferior_registers): Call store_regs and
	store_fpregs instead.
	(arm_linux_fetch_inferior_registers): Call fetch_fpregs and
	fetch_regs instead.