mailbox/omap: move the OMAP mailbox framework to drivers

The mailbox hardware (in OMAP) uses a queued mailbox interrupt
mechanism that provides a communication channel between processors
through a set of registers and their associated interrupt signals
by sending and receiving messages.

The OMAP mailbox framework/driver code is moved to be under
drivers/mailbox, in preparation for adapting to a common mailbox
driver framework. This allows the build for OMAP mailbox to be
enabled (it was disabled during the multi-platform support).

As part of the migration from plat and mach code:
- Kconfig symbols have been renamed to build OMAP1 or OMAP2+ drivers.
- mailbox.h under plat-omap/plat/include has been split into a public
  and private header files. The public header has only the API related
  functions and types.
- The module name mailbox.ko from plat-omap is changed to
  omap-mailbox.ko
- The module name mailbox_mach.ko from mach-omapX is changed as
    mailbox_omap1.ko for OMAP1
    mailbox_omap2.ko for OMAP2+

Cc: Tony Lindgren <tony@atomide.com>
[gregkh@linuxfoundation.org: ack for staging part]
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Omar Ramirez Luna <omar.ramirez@copitl.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index 543ad6a..e0facb3 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -1 +1,7 @@
 obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
+
+obj-$(CONFIG_OMAP_MBOX)		+= omap-mailbox.o
+obj-$(CONFIG_OMAP1_MBOX)	+= mailbox_omap1.o
+mailbox_omap1-objs		:= mailbox-omap1.o
+obj-$(CONFIG_OMAP2PLUS_MBOX)	+= mailbox_omap2.o
+mailbox_omap2-objs		:= mailbox-omap2.o