[media] coda: update CODA7541 to firmware 1.4.50

This patch splits the global workbuf into a global tempbuf and a per-context
workbuf, adds the codec mode aux register, and restores the work buffer
pointer on commands. With the new firmware, there is only a single set of
read/write pointers which need to be restored between context switches.
This allows more than four active contexts at the same time.
All auxiliary buffers are now allocated through a helper function to avoid
code duplication.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>