Revert "ACPICA: Interpreter: fix memory leak by using existing buffer"

This reverts commit 32cf1a12.

The 'exisitng buffer' in this case is the firmware provided table, and
we should not modify that in place. This fixes a crash on arm64 with
initrd table overrides, in which case the DSDT is not mapped with
read/write permissions.

Reported-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>