accel/amdxdna: include linux/slab.h

This driver fails to build in random configurations:

drivers/accel/amdxdna/aie2_solver.c: In function 'remove_partition_node':
drivers/accel/amdxdna/aie2_solver.c:121:9: error: implicit declaration of function 'kfree' [-Wimplicit-function-declaration]
  121 |         kfree(pt_node);
      |         ^~~~~
drivers/accel/amdxdna/aie2_solver.c: In function 'get_free_partition':
drivers/accel/amdxdna/aie2_solver.c:153:19: error: implicit declaration of function 'kzalloc' [-Wimplicit-function-declaration]
  153 |         pt_node = kzalloc(sizeof(*pt_node), GFP_KERNEL);

Add the missing include.

Fixes: c88d332 ("accel/amdxdna: Add hardware resource solver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241218085902.2684002-1-arnd@kernel.org

Author: arndb

drivers/accel/amdxdna/aie2_solver.c

@@ -8,6 +8,7 @@
 #include <drm/drm_print.h>
 #include <linux/bitops.h>
 #include <linux/bitmap.h>
+#include <linux/slab.h>
 
 #include "aie2_solver.h"