i2c: pxa: implement generic i2c bus recovery

Implement generic GPIO-based I2C bus recovery for the PXA I2C driver.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Wolfram Sang <wsa@kernel.org>