ARM: OMAP4: PM: Remove L4 wakeup depedency with MPU since errata fix exist now

ARM: OMAP4: PM: Remove L4 wakeup depedency with MPU since errata fix exist now

With commit bfd6d021 {ARM: OMAP3+: Implement timer workaround for errata
i103 and i767}, the sync and gptimer synchronization errata got fixed.

Hence the l4_wakeup static dependency with MPU can  can be removed
now. Static dependency was one of the proposed workaround but from
power savings perspective, it isn't an ideal workaround.

Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>