i2c: qup: Add device tree bindings information

The Qualcomm Universal Peripherial (QUP) wraps I2C mini-core and
provide input and output FIFO's for it. I2C controller can operate
as master with supported bus speeds of 100Kbps and 400Kbps.

Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
[bjorn: reformulated part of binding description
        added version to compatible
        cleaned up example]
Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
i2c: New bus driver for the Qualcomm QUP I2C controller

This bus driver supports the QUP i2c hardware controller in the Qualcomm SOCs.
The Qualcomm Universal Peripheral Engine (QUP) is a general purpose data path
engine with input/output FIFOs and an embedded i2c mini-core. The driver
supports FIFO mode (for low bandwidth applications) and block mode (interrupt
generated for each block-size data transfer).

Cc: Andy Gross <agross@codeaurora.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>