ARM: dts: OMAP2+: Add mailbox fifo and user information

The number of mailbox fifos and users (IP interrupts) are added
to the Mailbox DT nodes on OMAP2420, OMAP2430, OMAP3, and OMAP5
family of SoCs through the DT properties "ti,mbox-num-fifos" and
"ti,mbox-num-users" properties. This data represents the same data
that used to be represented in hwmod attribute data through the
.num_fifos and .num_users fields previously.

Signed-off-by: Suman Anna <s-anna@ti.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Tony Lindgren <tony@atomide.com>