GPIO: PCA953X: Increase size of invert variable to support 24 bit

TCA6424 is a low voltage 24 bit I2C and SMBus I/O expander of pca953x family
similar to its 16 bit predecessor TCA6416. It comes with three 8-bit active
Input, Output, Polarity Inversion and Configuration registers each. The polarity
of Input ports can be reversed by setting the appropiate bit in Polarity
Inversion registers.

The variables corresponding to Input, Output and Configuration registers have
already been updated to support 24 bit values. This patch thus updates the
invert variable of PCA953X platform data to support 24 bit.

Signed-off-by: Chandrabhanu Mahapatra <cmahapatra@ti.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>