isdn: move from strlcpy with unused retval to strscpy

Follow the advice of the below link and prefer 'strscpy' in this
subsystem. Conversion is 1:1 because the return value is not used.
Generated by a coccinelle script.

Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20220818210023.6889-1-wsa+renesas@sang-engineering.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/isdn/capi/kcapi.c

@@ -798,7 +798,7 @@ u16 capi20_get_serial(u32 contr, u8 serial[CAPI_SERIAL_LEN])
 	u16 ret;
 
 	if (contr == 0) {
-		strlcpy(serial, driver_serial, CAPI_SERIAL_LEN);
+		strscpy(serial, driver_serial, CAPI_SERIAL_LEN);
 		return CAPI_NOERROR;
 	}
 
@@ -806,7 +806,7 @@ u16 capi20_get_serial(u32 contr, u8 serial[CAPI_SERIAL_LEN])
 
 	ctr = get_capi_ctr_by_nr(contr);
 	if (ctr && ctr->state == CAPI_CTR_RUNNING) {
-		strlcpy(serial, ctr->serial, CAPI_SERIAL_LEN);
+		strscpy(serial, ctr->serial, CAPI_SERIAL_LEN);
 		ret = CAPI_NOERROR;
 	} else
 		ret = CAPI_REGNOTINSTALLED;