[media] Remove staging/lirc/lirc_i2c driver

This driver duplicates the same functionality found at ir-kbd-i2c.
There were a few missing key parsers that were added by the previous
patches. The only thing left on lirc_i2c driver is the IR parsing
for Asus TV-Box and Creative/VisionTek BreakOut-Box.
Those devices use pcf8574 chip for IR.

They are old video adapters with TV tuners. Their code were never
merged upstream, and they are not chipped anymore. So, it is very
unlikely that someone would have interests on porting them to the
Linux Kernel.

Due to that, let's remove lirc_i2c, as all the remaining functionality
are already mapped via ir-kbd-i2c.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>