panfrost: Only take the fast paths on buffers aligned to block size

panfrost: Only take the fast paths on buffers aligned to block size

As the functions operate on 16-byte blocks.

Fixes this Valgrind error:

Invalid read of size 4
   at 0x5857568: swizzle_bpp1_align16 (pan_swizzle.c:85)
   by 0x585780F: panfrost_texture_swizzle (pan_swizzle.c:171)
   by 0x584F587: panfrost_tile_texture (pan_resource.c:489)
   by 0x584F641: panfrost_transfer_unmap (pan_resource.c:525)
   by 0x587718D: u_transfer_helper_transfer_unmap (u_transfer_helper.c:516)
   by 0x5875D85: pipe_transfer_unmap (u_inlines.h:515)
   by 0x5875F13: u_default_texture_subdata (u_transfer.c:80)
   by 0x53FFDC3: st_TexSubImage (st_cb_texture.c:1480)
   by 0x54005BB: st_TexImage (st_cb_texture.c:1709)
   by 0x5391353: teximage (teximage.c:3105)
   by 0x5391353: teximage_err (teximage.c:3132)
   by 0x5391B9B: _mesa_TexImage2D (teximage.c:3170)
   by 0x5097A77: shared_dispatch_stub_183 (glapi_mapi_tmp.h:18833)
 Address 0x1e94f1e8 is 0 bytes after a block of size 16 alloc'd
   at 0x483F5C8: malloc (vg_replace_malloc.c:299)
   by 0x584F47D: panfrost_transfer_map (pan_resource.c:467)
   by 0x587694D: u_transfer_helper_transfer_map (u_transfer_helper.c:243)
   by 0x5875EA7: u_default_texture_subdata (u_transfer.c:59)
   by 0x53FFDC3: st_TexSubImage (st_cb_texture.c:1480)
   by 0x54005BB: st_TexImage (st_cb_texture.c:1709)
   by 0x5391353: teximage (teximage.c:3105)
   by 0x5391353: teximage_err (teximage.c:3132)
   by 0x5391B9B: _mesa_TexImage2D (teximage.c:3170)
   by 0x5097A77: shared_dispatch_stub_183 (glapi_mapi_tmp.h:18833)
   by 0x4DA8AB: glu::CallLogWrapper::glTexImage2D(unsigned int, int, int, int, int, int, unsigned int, unsigned int, void const*) (in /home/tomeu/deqp-build/modules/gles2/deqp-gles2)

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Cc: 19.1 <mesa-stable@lists.freedesktop.org>