Hibernate: Call platform_begin before swsusp_shrink_memory

Call platform_begin() before swsusp_shrink_memory() so that we can
always allocate enough memory to save the ACPI NVS region from
platform_begin().

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Nigel Cunningham <nigel@tuxonice.net>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>