mb/51nb/x210: Remove duplicate ACPI power button device

This is copied from the Purism Librem 13v3, and is not needed, as the
standard fixed power button is used. It was removed for the Pursim
devices in commit 2d977b2dcb (mb/purism: remove duplicate ACPI power
button).

Change-Id: I8fe19b8fbcc11d859a75b3dc6b9bcc42c80d13f1
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41018
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Rafael Send <flyingfishfinger@gmail.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/mainboard/51nb/x210/acpi/mainboard.asl

@@ -17,18 +17,6 @@ Scope (\_SB)
 		}
 	}
 
-	Device (PWRB)
-	{
-		Name (_HID, EisaId ("PNP0C0C"))
-
-		Method (_STA)
-		{
-			Return (0xF)
-		}
-
-		Name (_PRW, Package () { 27, 4 })
-	}
-
 	Device (SLPB)
 	{
 		Name (_HID, EisaId ("PNP0C0E"))