Arm: Minor style cleanups

Arm: Minor style cleanups

*When reading a target description, do the ptrace check before picking the
 target description.

*In wmmxregset functions, declare the counter inside the for.

*Call arm_linux_init_hwbp_cap from in arm_arch_setup - it doesn't belong in
 arm_read_description.

gdb/ChangeLog:

	* arm-linux-nat.c (arm_linux_nat_target::read_description): Check
	ptrace earlier,

gdb/gdbserver/ChangeLog:

	* linux-arm-low.c (arm_fill_wmmxregset, arm_store_wmmxregset):
	Move counter inside for.
	(arm_read_description): Check ptrace earlier.
	(arm_arch_setup): Call arm_linux_init_hwbp_cap here.