pinctrl: qcom: Add support to enable TLMM emmc boot for mdm9607

Some sdhci controllers may need additional TLMM registers to
be configured to enable sdhci I/O lines. Update the documentation
for the device node property and pinctrl for mdm9607 target

Change-Id: Ib009e1fffac0a22a6f23d5346d460498c7e712e9
Signed-off-by: Venkatesh Yadav Abbarapu <vabbar@codeaurora.org>