soc: imx: gpc: fix initialiser format

Make the initialiers in imx_gpc_domains C99 format to fix the
following sparse warnings:

drivers/soc/imx/gpc.c:252:30: warning: obsolete array initializer, use C99 syntax
drivers/soc/imx/gpc.c:258:29: warning: obsolete array initializer, use C99 syntax
drivers/soc/imx/gpc.c:269:34: warning: obsolete array initializer, use C99 syntax
drivers/soc/imx/gpc.c:278:30: warning: obsolete array initializer, use C99 syntax

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Fixes: b0682d48

 ("soc: imx: gpc: use GPC_PGC_DOMAIN_* indexes")
Signed-off-by: Shawn Guo <shawnguo@kernel.org>