omap: Fix wrong condition check in while loop for mailbox and iommu2

It's worked fine so far since reset is done for the first time.

Reported-by: Juha Leppanen <juha_motorsportcom@luukku.com>
Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
Signed-off-by: Juha Leppanen <juha_motorsportcom@luukku.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>