rpmsg: Add snapshot of RPMSG drivers for lahaina

This snapshot is taken as of msm-4.19 'commit <d2f41beab007i>
("Merge "msm: npu: Add bandwidth monitor support"")'.

This change brings the rpmsg and rpmsg glink drivers up to date with
the fixes from msm-4.19. In addition, change the copyrights to SPDX format.

Also, irq_set_affinity and sched_setaffinity can not be used when compiling
a driver as a module. Hence, moving to module-friendly APIs.

Change-Id: Id8c0bd13535c91cbecb11445bf798be44083abb6
Signed-off-by: Jay Jayanna <jayanna@codeaurora.org>