wifi: mwifiex: mark OF related data as maybe unused

The driver can be compile tested with !CONFIG_OF making certain data
unused:

  drivers/net/wireless/marvell/mwifiex/sdio.c:498:34: error: ‘mwifiex_sdio_of_match_table’ defined but not used [-Werror=unused-const-variable=]
  drivers/net/wireless/marvell/mwifiex/pcie.c:175:34: error: ‘mwifiex_pcie_of_match_table’ defined but not used [-Werror=unused-const-variable=]

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230312132523.352182-1-krzysztof.kozlowski@linaro.org