Use boot based time for process start time and boot time in /proc

Use boot based time for process start time and boot time in /proc

Commit 411187fb05cd11676b0979d9fbf3291db69dbce2 caused boot time to move and
process start times to become invalid after suspend.  Using boot based time
for those restores the old behaviour and fixes the issue.

[akpm@linux-foundation.org: little cleanup]
Signed-off-by: Tomas Janousek <tjanouse@redhat.com>
Cc: Tomas Smetana <tsmetana@redhat.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>