i2c: qup: advertise SMBus transfers using RECV_LEN

This driver implements I2C_M_RECV_LEN, so it can advertise the SMBus
transfers needing it. This also enables client devices to check for the
RECV_LEN capability.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>