ia64: make reserve_elfcorehdr() static

There never was a reason for reserve_elfcorehdr() to be global.  Make the
function static, and move it before its sole caller.

Link: https://lkml.kernel.org/r/fe236cd73b64abc4abd03dd808cb015c907f4c8c.1629884459.git.geert+renesas@glider.be
Fixes: cee87af2

 ("[IA64] kexec: Use EFI_LOADER_DATA for ELF core header")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Jay Lan <jlan@sgi.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Simon Horman <horms@verge.net.au>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>