DaVinci: fix GPIO breakage after v4.19

This set of changes is needed to fix the broken GPIO support
for DaVinci boards in legacy mode after certain changes made to the
GPIO driver in 4.19, namely: commits 587f7a694f01 ("gpio: davinci: Use
dev name for label and automatic base selection") and eb3744a2dd01
("gpio: davinci: Do not assume continuous IRQ numbering").

* tag 'davinci-fixes-for-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/nsekhar/linux-davinci:
  ARM: davinci: dm644x: set the GPIO base to 0
  ARM: davinci: da830: set the GPIO base to 0
  ARM: davinci: dm355: set the GPIO base to 0
  ARM: davinci: dm646x: set the GPIO base to 0
  ARM: davinci: dm365: set the GPIO base to 0
  ARM: davinci: da850: set the GPIO base to 0
  gpio: davinci: restore a way to manually specify the GPIO base
  ARM: davinci: dm644x: define gpio interrupts as separate resources
  ARM: davinci: dm355: define gpio interrupts as separate resources
  ARM: davinci: dm646x: define gpio interrupts as separate resources
  ARM: davinci: dm365: define gpio interrupts as separate resources
  ARM: davinci: da8xx: define gpio interrupts as separate resources

Signed-off-by: Olof Johansson <olof@lixom.net>