i2c: qup: support SMBus block read

I2C QUP driver relies on SMBus emulation support from the framework.
To handle SMBus block reads, the driver should check I2C_M_RECV_LEN
flag and should read the first byte received as the message length.

The driver configures the QUP hardware to read one byte. Once the
message length is known from this byte, the QUP hardware is configured
to read the rest.

Signed-off-by: Naveen Kaje <nkaje@codeaurora.org>
Signed-off-by: Austin Christ <austinwc@codeaurora.org>
Reviewed-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>