arm: gcc-8: drivers/pinctrl/mediatek/../core.h:211:21: error: initializer element is not constant (struct group_desc)

[Naresh Kamboju]

Following build errors noticed on Linux next-20231204 tag with gcc-8 toolchain
for arm and arm64.

## Test Regressions (compared to next-20231201)
* arm, build
  - gcc-8-defconfig

* arm64, build
  - gcc-8-defconfig

Reported-by: Linux Kernel Functional Testing <lkft at linaro.org>

Build log arm and arm64:
------------
In file included from drivers/pinctrl/mediatek/pinctrl-moore.h:21,
                 from drivers/pinctrl/mediatek/pinctrl-mt7623.c:11:
drivers/pinctrl/mediatek/../core.h:211:21: error: initializer element
is not constant
 (struct group_desc) {      \
                     ^

Links:
- https://storage.tuxsuite.com/public/linaro/lkft/builds/2Z43zPIMN6vxVKd9rKJFdOKXpox/
 - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20231204/testrun/21472198/suite/build/test/gcc-8-defconfig/details/
 - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20231204/testrun/21472585/suite/build/test/gcc-8-defconfig/details/
 - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20231204/testrun/21472800/suite/build/test/gcc-8-defconfig/history/

Steps to reproduce:
---------------
# tuxmake --runtime podman --target-arch arm64 --toolchain gcc-8
--kconfig defconfig



--
Linaro LKFT
https://lkft.linaro.org