powerpc: eSPI and eSPI controller support

Signed-off-by: Mingkai Hu <Mingkai.hu@freescale.com>
Singed-off-by: Jerry Huang <Chang-Ming.Huang@freescale.com>
Signed-off-by: Shaohui Xie <b21989@freescale.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>