staging: greybus: loopback: use sysfs_emit in sysfs show functions

staging: greybus: loopback: use sysfs_emit in sysfs show functions

As per the kernel's documentation, sysfs_emit() is the preferred way
to format strings for sysfs attributes. It handles buffer overruns
safely. Replace sprintf calls with sysfs_emit across all loopback
sysfs show macros.

Signed-off-by: Luis Soza Rodriguez <contact@sluisr.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/20260309230507.4931-1-contact@sluisr.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>