x86/insn: remove pcommit

x86/insn: remove pcommit

The pcommit instruction is being deprecated in favor of either ADR
(asynchronous DRAM refresh: flush-on-power-fail) at the platform level, or
posted-write-queue flush addresses as defined by the ACPI 6.x NFIT (NVDIMM
Firmware Interface Table).

Cc: Thomas Gleixner <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Cc: Josh Poimboeuf <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Xiao Guangrong <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Ross Zwisler <[email protected]>
Acked-by: Ingo Molnar <[email protected]>
Signed-off-by: Dan Williams <[email protected]>