[IA64] kexec: Minor enhancement to includes in crash.c

linux/uaccess.h was being included, but it seems that
really the following includes are needed.

asm/page.h: for __va() and PAGE_SHIFT
asm/uaccess.h: for copy_to_user()

I guess that linux/uaccess.h pulls in both asm/page.h and asm/uaccess.h.
I notices this while backporting the code to xen's linux-2.6.16.33,
which does not have linux/uaccess.h. I'm posting it as I think it is a
correct, though somewhat cosmetic fix.

Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Tony Luck <tony.luck@intel.com>