x86/jump-label: Use best default nops for inital jump label calls

As specified by H. Peter Anvin, the best nops for x86 without knowing
the running computer is:

32bit:
  0x3e, 0x8d, 0x74, 0x26, 0x00 also known as GENERIC_NOP5_ATOMIC

64bit:
  0x0f, 0x1f, 0x44, 0x00, 0x00  also known as P6_NOP5_ATOMIC

Currently the default nop that is used by jump label is:

 0xe9 0x00 0x00 0x00 0x00

Which is really a 5byte jump to the next position.

It's better to use a real nop than a jmp.

Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Jason Baron <jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>