drm/imagination: Ensure PVR_MIPS_PT_PAGE_COUNT is never zero

When the host page size was more than 4 times larger than the FW page
size, this macro evaluated to zero resulting in zero-sized arrays.

Use DIV_ROUND_UP() to ensure the correct behavior.

Reported-by: 20240228012313.5934-1-yaolu@kylinos.cn
Closes: https://lore.kernel.org/dri-devel/20240228012313.5934-1-yaolu@kylinos.cn
Link: https://lore.kernel.org/dri-devel/20240228012313.5934-1-yaolu@kylinos.cn
Fixes: 927f3e02 ("drm/imagination: Implement MIPS firmware processor and MMU support")
Cc: stable@vger.kernel.org
Signed-off-by: Matt Coster <matt.coster@imgtec.com>
Reviewed-by: Frank Binns <frank.binns@imgtec.com>

drivers/gpu/drm/imagination/pvr_fw_mips.h

@@ -7,13 +7,14 @@
 #include "pvr_rogue_mips.h"
 
 #include <asm/page.h>
+#include <linux/math.h>
 #include <linux/types.h>
 
 /* Forward declaration from pvr_gem.h. */
 struct pvr_gem_object;
 
-#define PVR_MIPS_PT_PAGE_COUNT ((ROGUE_MIPSFW_MAX_NUM_PAGETABLE_PAGES * ROGUE_MIPSFW_PAGE_SIZE_4K) \
-				>> PAGE_SHIFT)
+#define PVR_MIPS_PT_PAGE_COUNT DIV_ROUND_UP(ROGUE_MIPSFW_MAX_NUM_PAGETABLE_PAGES * ROGUE_MIPSFW_PAGE_SIZE_4K, PAGE_SIZE)
+
 /**
  * struct pvr_fw_mips_data - MIPS-specific data
  */