watchdog: rzv2h_wdt: Add missing MODULE_LICENSE tag to fix modpost error

Add the missing `MODULE_LICENSE()` tag to the `rzv2h_wdt` driver, which
resolves the following modpost error when built as a module:

ERROR: modpost: missing MODULE_LICENSE() in drivers/watchdog/rzv2h_wdt.o

Fixes: f6febd0a30b6 ("watchdog: Add Watchdog Timer driver for RZ/V2H(P)")
Reported-by: Stephen Rothwell <[e-mail]>
Signed-off-by: Lad Prabhakar <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/rzv2h_wdt.c

···
 module_platform_driver(rzv2h_wdt_driver);
 MODULE_AUTHOR("Lad Prabhakar <[e-mail]>");
 MODULE_DESCRIPTION("Renesas RZ/V2H(P) WDT Watchdog Driver");
+MODULE_LICENSE("GPL");