mmc: sdhci: Fix sdhci_led_control() path

The SDHC driver registers sdhci_led_control() with LED class device
and it gets invoked when the sysfs entry - /sys/class/leds/mmcX::
is updated. This function access SDHC Host control register (0x28)
and hence, check the driver state (runtime suspended/clocks gated)
before accessing it. Otherwise, it may result in unclocked access
resulting in system failure.

CRs-fixed: 480596
Change-Id: Icef51f02abb54316710df30429fec875030d42d9
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>