V4L/DVB (4875): budget-ci IR: groundwork for following patches

This patch lays down some groundwork for later budget-ci patches. The bulk
of this consists of moving a few members into a new struct and renaming a
few of them.
It also allocates extra space for the device name (the "name" field in
/proc/bus/input/devices and in the relevant sysfs dir) to avoid truncation
and uses snprintf rather than sprintf in case the extra space shouldn't be
enough.
Taken from Darren Salt's dvb-ir patchset

Signed-off-by: Darren Salt <linux@youmustbejoking.demon.co.uk>
Signed-off-by: David Hardeman <david@hardeman.nu>
Signed-off-by: Andrew de Quincey <adq_dvb@lidskialf.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>