staging: gpib: use int type to store negative error codes

staging: gpib: use int type to store negative error codes

The "ret" variable is used to store the return from bb_write() returns
either zero on success or negative error codes on failure.  Storing the
error codes in size_t which is an unsigned long, doesn't cause an issue
at runtime but it's ugly as pants.  Change "ret" from size_t to int
type.  No effect on runtime.

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/20250826123208.300145-1-rongqianfeng@vivo.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>