mach-tegra: tegra_mpdecision: rename cpu locks

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
mach-tegra: tegra_mpdecision: make tegra_mpdec_work_thread independent of the number of available cores (dual/quad)

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>