mfd: htc-i2cpld depends on GPIOLIB

htc-i2cpld should depend on GPIOLIB, otherwise there are many
build errors:

drivers/mfd/htc-i2cpld.c:50: error: field 'chip_out' has incomplete type
drivers/mfd/htc-i2cpld.c:54: error: field 'chip_in' has incomplete type
drivers/mfd/htc-i2cpld.c:243: warning: type defaults to 'int' in declaration of '__mptr'
drivers/mfd/htc-i2cpld.c:243: warning: initialization from incompatible pointer type
drivers/mfd/htc-i2cpld.c:278: warning: type defaults to 'int' in declaration of '__mptr'
drivers/mfd/htc-i2cpld.c:278: warning: initialization from incompatible pointer type
drivers/mfd/htc-i2cpld.c:282: warning: type defaults to 'int' in declaration of '__mptr'
drivers/mfd/htc-i2cpld.c:282: warning: initialization from incompatible pointer type
drivers/mfd/htc-i2cpld.c:315: error: dereferencing pointer to incomplete type
drivers/mfd/htc-i2cpld.c:322: warning: type defaults to 'int' in declaration of '__mptr'
drivers/mfd/htc-i2cpld.c:322: warning: initialization from incompatible pointer type
drivers/mfd/htc-i2cpld.c:467+: error: dereferencing pointer to incomplete type [19X]
drivers/mfd/htc-i2cpld.c:490: error: implicit declaration of function 'gpiochip_add'
drivers/mfd/htc-i2cpld.c:504: error: implicit declaration of function 'gpiochip_remove'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>