Kconfig: Remove ACPI_SSDTX_NUM.

Its scope is limited to a single mainboard and is only to go through ifdef.
Kill it and move the value to the code.

Change-Id: I76a87e2790d57dee8f37b51e33d0689fffd3a59d
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/7135
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>

src/Kconfig

@@ -356,10 +356,6 @@ config HAVE_ACPI_SLIC
 	bool
 	default n
 
-config ACPI_SSDTX_NUM
-	int
-	default 0
-
 config HAVE_HARD_RESET
 	bool
 	default n