ARM: net: bpf: improve 64-bit sign-extended immediate load

Improve the 64-bit sign-extended immediate from:

  mov     r6, #1
  str     r6, [fp, #-52]  ; 0xffffffcc
  mov     r6, #0
  str     r6, [fp, #-48]  ; 0xffffffd0

to:

  mov     r6, #1
  mov     r7, #0
  strd    r6, [fp, #-52]  ; 0xffffffcc

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>