ARM: SAMSUNG: Restore Samsung PM Debug functionality

Due to recently merged patches and previous merge conflicts, the Samsung
PM Debug functionality no longer can be enabled. This patch fixes
incorrect dependency of SAMSUNG_PM_DEBUG on an integer symbol and adds
missing header inclusion.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>