staging: gpib: gpio: Return error value from gpib_register_driver()

The function gpib_register_driver() can fail and does not return an
error value if it fails.

Return the error value if gpib_register_driver() fails. Add pr_err()
statement indicating the fail and also the error value.

Signed-off-by: Nihar Chaithanya <niharchaithanya@gmail.com>
Link: https://lore.kernel.org/r/20241230185633.175690-9-niharchaithanya@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: niharcy

drivers/staging/gpib/gpio/gpib_bitbang.c

@@ -1341,7 +1341,12 @@ return_to_local : bb_return_to_local,
 
 static int __init bb_init_module(void)
 {
-	gpib_register_driver(&bb_interface, THIS_MODULE);
+	int result = gpib_register_driver(&bb_interface, THIS_MODULE);
+
+	if (result) {
+		pr_err("gpib_bitbang: gpib_register_driver failed: error = %d\n", result);
+		return result;
+	}
 
 	dbg_printk(0, "module loaded with pin map \"%s\"%s\n",
 		   pin_map, (sn7516x_used) ? " and SN7516x driver support" : "");