Staging: most: avoid possible integer overflow

This patch prevents a potential integer overlow.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/most/mostcore/core.c

@@ -1260,7 +1260,7 @@ int arm_mbo_chain(struct most_c_obj *c, int dir, void (*compl)(struct mbo *))
 	unsigned int i;
 	int retval;
 	struct mbo *mbo;
-	u16 coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
+	u32 coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
 
 	atomic_set(&c->mbo_nq_level, 0);