dt-bindings: mfd: syscon: Document the GPR syscon for the NXP S32 SoCs

The NXP S32 SoCs have a GPR region which is used by a variety of
drivers.  Some examples of the registers in this region are:

  * DDR_PMU_IRQ
  * GMAC0_PHY_INTF_SEL
  * GMAC1_PHY_INTF_SEL
  * PFE_EMACS_INTF_SEL
  * PFE_COH_EN
  * PFE_PWR_CTRL
  * PFE_EMACS_GENCTRL1
  * PFE_GENCTRL3

Use the syscon interface to access these registers.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Link: https://patch.msgid.link/792d3f59b9f519529b94e673faf70d77c4b61fb3.1765806521.git.dan.carpenter@linaro.org
Signed-off-by: Lee Jones <lee@kernel.org>

Author: Dan Carpenter

Documentation/devicetree/bindings/mfd/syscon.yaml

@@ -102,6 +102,8 @@ select:
           - mstar,msc313-pmsleep
           - nuvoton,ma35d1-sys
           - nuvoton,wpcm450-shm
+          - nxp,s32g2-gpr
+          - nxp,s32g3-gpr
           - qcom,apq8064-mmss-sfpb
           - qcom,apq8064-sps-sic
           - rockchip,px30-qos
@@ -212,6 +214,8 @@ properties:
               - mstar,msc313-pmsleep
               - nuvoton,ma35d1-sys
               - nuvoton,wpcm450-shm
+              - nxp,s32g2-gpr
+              - nxp,s32g3-gpr
               - qcom,apq8064-mmss-sfpb
               - qcom,apq8064-sps-sic
               - rockchip,px30-qos