pinctrl: scu: Depend on IMX_SCU

Otherwise building fails with only PINCTRL_IMX_SCU selected:

    aarch64-linux-gnu-ld: drivers/pinctrl/freescale/pinctrl-scu.o: in function `imx_pinctrl_sc_ipc_init':
    pinctrl-scu.c:(.text+0x10): undefined reference to `imx_scu_get_handle'
    aarch64-linux-gnu-ld: pinctrl-scu.c:(.text+0x10): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `imx_scu_get_handle'
    aarch64-linux-gnu-ld: drivers/pinctrl/freescale/pinctrl-scu.o: in function `imx_pinconf_get_scu':
    pinctrl-scu.c:(.text+0x64): undefined reference to `imx_scu_call_rpc'
    aarch64-linux-gnu-ld: pinctrl-scu.c:(.text+0x64): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `imx_scu_call_rpc'
    aarch64-linux-gnu-ld: drivers/pinctrl/freescale/pinctrl-scu.o: in function `imx_pinconf_set_scu':
    pinctrl-scu.c:(.text+0x104): undefined reference to `imx_scu_call_rpc'
    aarch64-linux-gnu-ld: pinctrl-scu.c:(.text+0x104): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `imx_scu_call_rpc'
    make: *** [Makefile:1038: vmlinux] Error 1

Signed-off-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Status Job ID Name Coverage
  Build
failed #6898
build

failed #6757
build

 
  Test
skipped #6759
allowed to fail
code_quality
skipped #6758
test
 
Name Stage Failure
failed
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