tools/testing/radix-tree: add missing MODULE_DESCRIPTION definition

Userspace builds of the radix-tree testing suite fails because of commit
test_maple_tree: add the missing MODULE_DESCRIPTION() macro.  Add the
proper defines to tools/testing/radix-tree/maple.c and
tools/testing/radix-tree/xarray.c so MODULE_DESCRIPTION has a definition. 
This allows the build to succeed.

Link: https://lkml.kernel.org/r/20240617195221.106565-1-sidhartha.kumar@oracle.com
Fixes: 9f8090e8c4d1 ("test_maple_tree: add the missing MODULE_DESCRIPTION() macro")
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Jeff Johnson <quic_jjohnson@quicinc.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/radix-tree/maple.c

@@ -19,6 +19,7 @@
 #define module_init(x)
 #define module_exit(x)
 #define MODULE_AUTHOR(x)
+#define MODULE_DESCRIPTION(X)
 #define MODULE_LICENSE(x)
 #define dump_stack()	assert(0)
 

tools/testing/radix-tree/xarray.c

@@ -10,6 +10,7 @@
 #define module_init(x)
 #define module_exit(x)
 #define MODULE_AUTHOR(x)
+#define MODULE_DESCRIPTION(X)
 #define MODULE_LICENSE(x)
 #define dump_stack()	assert(0)