Impact: save kernel .text by loosening kexec page alignment

This patch removes PAGE_SIZE alignment from relocate_kernel(). Before
kexec jump patches are merged, control page is mapped to
relocate_kernel in kexec page tables, so relocate_kernel must be
PAGE_SIZE aligned. Now, control page is mapped to identity mapped
address, so relocate_kernel need not to be PAGE_SIZE aligned any
more. This can reduce a few KB from kernel text segement.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>