x86/apic: Fix use of X{,2}APIC_ENABLE in asm with older binutils

"x86/smpboot: Support parallel startup of secondary CPUs" adds the first use
of X2APIC_ENABLE in assembly, but older binutils don't tolerate the UL suffix.

Switch to using BIT() instead.

Fixes: 7e75178a ("x86/smpboot: Support parallel startup of secondary CPUs")
Reported-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Link: https://lore.kernel.org/r/20230522105738.2378364-1-andrew.cooper3@citrix.com