arm64: proton-pack: use sysfs_emit in sysfs show functions

arm64: proton-pack: use sysfs_emit in sysfs show functions

Replace sprintf() with sysfs_emit() in sysfs show functions, which is
preferred for formatting sysfs output because it provides safer bounds
checking.

While the current code only emits fixed strings that fit easily within
PAGE_SIZE, use sysfs_emit() to follow secure coding best practices.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Will Deacon <will@kernel.org>