Use gdb::array_view for setting value bytes in trad-frame

Use gdb::array_view for setting value bytes in trad-frame

This patch updates the functions setting value bytes in trad-frame to use
a gdb::array_view instead of passing a buffer and a size.

gdb/ChangeLog:

2021-01-19  Luis Machado  <luis.machado@linaro.org>

	* aarch64-linux-tdep.c (aarch64_linux_restore_vreg): Pass in an
	array_view.
	* trad-frame.c (trad_frame_set_value_bytes): Use gdb::array_view
	instead of buffer and size.
	(trad_frame_set_reg_value_bytes): Likewise.
	* trad-frame.h (trad_frame_set_reg_value_bytes): Likewise.
	(trad_frame_set_value_bytes): Likewise.