ARM: 7160/1: setup: avoid overflowing {elf,arch}_name from proc_info_list

setup_processor copies the arch_name and elf_name fields out of the
selected proc_info_list into two fixed size buffers.

Since the proc_info_list structure is defined in a proc_*.S assembly
file, this can lead to subtle errors if the strings defined there are
too long (for example, corrupting the machine ID).

This patch uses snprintf instead of sprintf to ensure that these buffers
are not overrun.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>