Tweaked fs/dache, mm/page-writeback and mm/page_alloc

Signed-off-by: Willi Ye <williye97@gmail.com>

Conflicts:
	mm/page-writeback.c
	mm/page_alloc.c
fs/dcache.c: adaptive vfs_cache_pressure on suspend / resume

low vfs_cache pressure values save battery while idle, while
a low value also causes stutter with longer up times.

Signed-off-by: Willi Ye <williye97@gmail.com>

Conflicts:
	fs/dcache.c
fs/dache.c / mm/page-writeback.c: allow modification of dirty_-values and cache_pressure despite the dynamic suspend/resume values

Conflicts:
	mm/page-writeback.c
Increase the default vfs_cache_pressure to 125 so that more zcache is utilized
Define default VFS cache pressure according to Cleancache definition.