'current' is also defined in asm-generic/current.h.

When compiling this driver for older kernels with the media_build system,
this header is included via compat.h and it no longer compiles. Rename
current to cur.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>