watchdog: imx2_wdg: Declare local symbols static

watchdog: imx2_wdg: Declare local symbols static

0-day complains:

drivers/watchdog/imx2_wdt.c:442:22: sparse:
	symbol 'imx_wdt' was not declared. Should it be static?
drivers/watchdog/imx2_wdt.c:446:22: sparse:
	symbol 'imx_wdt_legacy' was not declared. Should it be static?

Declare as static variables.

Fixes: e42c73f1ef0d ("watchdog: imx2_wdg: suspend watchdog in WAIT mode")
Cc: Andrej Picej <andrej.picej@norik.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230228151648.4087637-1-linux@roeck-us.net
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>