clang-nightly: vdso/compat_gettimeofday.h:152:15: error: instruction variant requires ARMv6 or later

[Naresh Kamboju]

Following build errors noticed on Linux next-20231204 tag with clang-nightly
for arm and arm64.

## Test Regressions (compared to next-20231201)
* arm64, build
  - clang-nightly-defconfig
  - clang-nightly-defconfig-40bc7ee5
  - clang-nightly-lkftconfig
  - clang-nightly-lkftconfig-kselftest

* arm, build
  - clang-nightly-allnoconfig
  - clang-nightly-axm55xx_defconfig
  - clang-nightly-bcm2835_defconfig
  - clang-nightly-clps711x_defconfig
  - clang-nightly-defconfig
  - clang-nightly-exynos_defconfig
  - clang-nightly-imx_v6_v7_defconfig
  - clang-nightly-keystone_defconfig
  - clang-nightly-lkftconfig
  - clang-nightly-lkftconfig-kselftest
  - clang-nightly-omap2plus_defconfig
  - clang-nightly-pxa910_defconfig
  - clang-nightly-s3c6400_defconfig
  - clang-nightly-s5pv210_defconfig
  - clang-nightly-sama5_defconfig
  - clang-nightly-shmobile_defconfig
  - clang-nightly-tinyconfig
  - clang-nightly-u8500_defconfig
  - clang-nightly-vexpress_defconfig


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


Build log on arm64:
---------
In file included from lib/vdso/gettimeofday.c:5:
In file included from include/vdso/datapage.h:135:
arch/arm64/include/asm/vdso/compat_gettimeofday.h:152:15: error:
instruction variant requires ARMv6 or later
  152 |         asm volatile("mov %0, %1" : "=r"(ret) : "r"(_vdso_data));
      |                      ^
<inline asm>:1:2: note: instantiated into assembly here
    1 |         mov r4, r1
      |         ^
In file included from <built-in>:3:
lib/vdso/gettimeofday.c:139:3: error: invalid instruction
  139 |                 smp_rmb();
      |                 ^

Build log on arm:
---------
In file included from arch/arm/vfp/vfpmodule.c:23:
arch/arm/include/asm/cp15.h:101:2: error: instruction requires: data-barriers
  101 |         isb();
      |         ^


Links:
arm64
 - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20231204/testrun/21471527/suite/build/test/clang-nightly-defconfig/details/

arm
 - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20231204/testrun/21471941/suite/build/test/clang-nightly-exynos_defconfig/log
 - https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20231204/testrun/21471941/suite/build/test/clang-nightly-exynos_defconfig/details/



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