uapi: Add QTI specific header for UART

Create QTI specific header for UART IOCTLs. Bluetooth uses the IOCTL
to control UART clock/power states.

Choose higher numerical value for UART IOCTL macros to avoid any
conflict with upstream addition for new IOCTL.

Change-Id: I6dbabe30f5a12b5bc21cfe8fb16cdccfcc770484
Signed-off-by: Akash Asthana <akashast@codeaurora.org>