misc: mic: scif: scif_api: Remove set but unused variable 'read_size'

misc: mic: scif: scif_api: Remove set but unused variable 'read_size'

'read_size' appears to have been assigned, but never used since the
SCIF messaging and node enumeration APIs were introduced in 2015.
Makes sense to simply remove it.

Fixes the following W=1 warning:

 drivers/misc/mic/scif/scif_api.c: In function ‘_scif_recv’:
 drivers/misc/mic/scif/scif_api.c:1000:6: warning: variable ‘read_size’ set but not used [-Wunused-but-set-variable]
 1000 | int read_size;
 | ^~~~~~~~~

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200701083118.45744-19-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>