soc: qcom: Add GSBI driver

The GSBI (General Serial Bus Interface) driver controls the overarching
configuration of the shared serial bus infrastructure on APQ8064, IPQ8064, and
earlier QCOM processors.  The GSBI supports UART, I2C, SPI, and UIM
functionality in various combinations.

Signed-off-by: Andy Gross <agross@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>