arm64: rename dump_instr as dump_kernel_instr

In traps.c, only __die calls dump_instr.
However, this function has sub-function as __dump_instr.

dump_kernel_instr can replace those functions.
By using aarch64_insn_read, it does not have to change fs to KERNEL_DS.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: jinho lim <jordan.lim@samsung.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>