OMAP: PM debugfs removing OMAP3 hardcodings.

This patch removes omap3 hardcodings from pm-debug.c
so that enabling PM debugfs support does break compilation
for other OMAP's. This is a preparatory patch for supporting
OMAP4 pm entries through PM debugfs.

Signed-off-by: Thara Gopinath <thara@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>