imx: soc: Select REGMAP_MMIO

The imx-gpcv2 driver needs Regmap MMIO. Select it, and fix:

drivers/soc/imx/gpcv2.c:420:34: error: array type has incomplete element type ‘struct regmap_range’
  420 | static const struct regmap_range imx7_yes_ranges[] = {
      |                                  ^~~~~~~~~~~~~~~
drivers/soc/imx/gpcv2.c:421:17: error: implicit declaration of function ‘regmap_reg_range’; did you mean ‘remap_pfn_range’? [-Werror=implicit-function-declaration]
  421 |                 regmap_reg_range(GPC_LPCR_A_CORE_BSC,
      |                 ^~~~~~~~~~~~~~~~
      |                 remap_pfn_range

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>