libnvdimm/nfit_test: Fix acpi_handle redefinition

After commit 62974fc ("libnvdimm: Enable unit test infrastructure
compile checks"), clang warns:

In file included from
../drivers/nvdimm/../../tools/testing/nvdimm/test/iomap.c:15:
../drivers/nvdimm/../../tools/testing/nvdimm/test/nfit_test.h:206:15:
warning: redefinition of typedef 'acpi_handle' is a C11 feature
[-Wtypedef-redefinition]
typedef void *acpi_handle;
              ^
../include/acpi/actypes.h:424:15: note: previous definition is here
typedef void *acpi_handle;      /* Actually a ptr to a NS Node */
              ^
1 warning generated.

The include chain:

iomap.c ->
    linux/acpi.h ->
        acpi/acpi.h ->
            acpi/actypes.h
    nfit_test.h

Avoid this by including linux/acpi.h in nfit_test.h, which allows us to
remove both the typedef and the forward declaration of acpi_object.

Link: ClangBuiltLinux#660
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20190918042148.77553-1-natechancellor@gmail.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Author: nathanchance

tools/testing/nvdimm/test/nfit_test.h

@@ -4,6 +4,7 @@
  */
 #ifndef __NFIT_TEST_H__
 #define __NFIT_TEST_H__
+#include <linux/acpi.h>
 #include <linux/list.h>
 #include <linux/uuid.h>
 #include <linux/ioport.h>
@@ -202,9 +203,6 @@ struct nd_intel_lss {
 	__u32 status;
 } __packed;
 
-union acpi_object;
-typedef void *acpi_handle;
-
 typedef struct nfit_test_resource *(*nfit_test_lookup_fn)(resource_size_t);
 typedef union acpi_object *(*nfit_test_evaluate_dsm_fn)(acpi_handle handle,
 		 const guid_t *guid, u64 rev, u64 func,