ARM: pxa2xx: reorganize I2C files

This patch moves the platform data definition from
arch/arm/plat-pxa/include/plat/i2c.h to include/linux/i2c/pxa-i2c.h so
it can be accessed from x86 the same way as on ARM.

This change should make no functional change to the PXA code. The move
is verified by building the following defconfigs:
  cm_x2xx_defconfig corgi_defconfig em_x270_defconfig ezx_defconfig
  imote2_defconfig pxa3xx_defconfig spitz_defconfig zeus_defconfig
  raumfeld_defconfig magician_defconfig mmp2_defconfig pxa168_defconfig
  pxa910_defconfig

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Dirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>