[PATCH v2 4/9] nds32: Fix drivers/gpu/drm/udl/udl_fb.c building error by defining PAGE_SHARED

It broke the 'allmodconfig' build. drivers/gpu/drm/udl/udl_fb.c: In function 'udl_fb_mmap': drivers/gpu/drm/udl/udl_fb.c:183:52: error: 'PAGE_SHARED' undeclared (first use in this function) if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))

[PATCH v2 4/9] nds32: Fix drivers/gpu/drm/udl/udl_fb.c building error by defining PAGE_SHARED

It broke the 'allmodconfig' build. drivers/gpu/drm/udl/udl_fb.c: In function 'udl_fb_mmap': drivers/gpu/drm/udl/udl_fb.c:183:52: error: 'PAGE_SHARED' undeclared (first use in this function) if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))