ARM: davinci: PM: Free resources in error handling path in 'davinci_pm_init'

If 'sram_alloc' fails, we need to free already allocated resources.

Fixes: aa9aa1ec ("ARM: davinci: PM: rework init, remove platform device")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>