efi_loader: Ensure memory allocations are page aligned

efi_loader: Ensure memory allocations are page aligned

When the max_addr parameter of efi_find_free_memory() is within bounds
of an existing map and fits the reservation, we just return that address
as allocation value.

That breaks however if max_addr is not page aligned. So ensure that it
always comes to us page aligned, simplifying the allocation logic.

Without this, I've seen breakage where we were allocating pages at -1U
(32bit) which fits into a region that spans beyond 0x100000000. In that
case, we would return 0xffffffff as a valid memory allocation, although
we usually do guarantee they are all page aligned.

Fix this by aligning the max address argument always.

Signed-off-by: Alexander Graf <agraf@suse.de>