next-20250819: sdhci-cadence.c error variable 'hrs37_mode' is uninitialized when used here [-Werror,-Wuninitialized]

[Naresh Kamboju]

The following build warnings / errors noticed with arm64 defconfig
and x86 allyesconfig with clang-20 and clang-nightly toolchains.

Regression Analysis:
- New regression? yes
- Reproducibility? yes

Build regression: next-20250819 sdhci-cadence.c error variable
'hrs37_mode' is uninitialized when used here [-Werror,-Wuninitialized]

Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>

## Build log
drivers/mmc/host/sdhci-cadence.c:297:9: error: variable 'hrs37_mode'
is uninitialized when used here [-Werror,-Wuninitialized]
  297 |         writel(hrs37_mode, hrs37_reg);
      |                ^~~~~~~~~~
drivers/mmc/host/sdhci-cadence.c:291:16: note: initialize the variable
'hrs37_mode' to silence this warning
  291 |         u32 hrs37_mode;
      |                       ^
      |                        = 0

## Source
* Kernel version: 6.17.0-rc2
* Git tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git
* Git describe: next-20250819
* Git commit: 3ac864c2d9bb8608ee236e89bf561811613abfce
* Architectures: arm64 x86
* Toolchains: clang-20
* Kconfigs: defconfig and allyesconfig

## Build
* Build log: https://qa-reports.linaro.org/api/testruns/29595553/log_file/
* Build details x86:
https://regressions.linaro.org/lkft/linux-next-master/next-20250819/log-parser-build-clang/clang-compiler-drivers_mmc_host_sdhci-cadence_c-error-variable-hrs_mode-is-uninitialized-when-used-here/
* Build details arm64:
https://regressions.linaro.org/lkft/linux-next-master/next-20250819/log-parser-build-clang/clang-compiler-drivers_mmc_host_sdhci-cadence_c-warning-variable-hrs_mode-is-uninitialized-when-used-here/
* Build plan: https://tuxapi.tuxsuite.com/v1/groups/linaro/projects/lkft/builds/31UgO4773uaneRjyDrf418EXcDd
* Build link: https://storage.tuxsuite.com/public/linaro/lkft/builds/31UgO4773uaneRjyDrf418EXcDd/
* Kernel config:
https://storage.tuxsuite.com/public/linaro/lkft/builds/31UgO4773uaneRjyDrf418EXcDd/config

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