ARM64 / ACPI: Don't unflatten device tree if acpi=force is passed

Since the policy is that once we pass acpi=force in the early
param, we will not unflatten device tree even if ACPI is disabled
in ACPI table init fails, so fix the code by comparinging both
acpi_disabled and param_acpi_force before the device tree is
unflattened.

CC: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/kernel/acpi.c

@@ -43,7 +43,7 @@ static int enabled_cpus;
 static bool bootcpu_valid  __initdata;
 
 static bool param_acpi_off __initdata;
-static bool param_acpi_force __initdata;
+bool param_acpi_force __initdata;
 
 static int __init parse_acpi(char *arg)
 {