ARM: imx: Add iram allocator functions

Add IRAM(Internal RAM) allocation functions using GENERIC_ALLOCATOR.
The allocation size is 4KB multiples to guarantee alignment. The
idea for these functions is for i.MX platforms to use them
to dynamically allocate IRAM usage.

Applies on 2.6.36-rc7

Signed-off-by: Dinh Nguyen <Dinh.Nguyen@freescale.com>
Reviewed-by: Amit Kucheria <amit.kucheria@canonical.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>