Revert "arm64: jump_label: use constraints "Si" instead of "i""

This reverts commit f9daab0a.

Geert reports that his particular GCC 5.5 vintage toolchain fails to
build an arm64 defconfig because of this change:

 |    arch/arm64/include/asm/jump_label.h:25:2: error: invalid 'asm':
 | invalid operand
 |     asm goto(
      ^
Aopparently, this is something we claim to support, so let's revert back
to the old jump label constraint for now while discussions about raising
the minimum GCC version are ongoing.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/CAMuHMdX+6fnAf8Hm6EqYJPAjrrLO9T7c=Gu3S8V_pqjSDowJ6g@mail.gmail.com


Signed-off-by: Will Deacon <will@kernel.org>