staging: greybus: Remove redundant variable 'mask'

staging: greybus: Remove redundant variable 'mask'

The variable mask is being assigned and bit-set but it is never
being used apart from this. The variable is redundant and can
be removed.

Cleans up clang scan build warning:
drivers/staging/greybus/audio_topology.c:764:15: warning: variable 'mask'
set but not used [-Wunused-but-set-variable]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Acked-by: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Link: https://lore.kernel.org/r/20240229120541.219429-1-colin.i.king@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>