gpio: pca953x handles more chips, i2c fault codes

Minor updates to the pca953x GPIO expander driver: handle several more
compatible parts, and stop assuming that the I2C layer's return codes are
garbage (that's now been fixed).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>