drm/imagination: Fix a couple of spelling mistakes in literal strings

There are a couple of spelling mistakes in literal strings in the
stid_fmts array. Fix these.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reviewed-by: Frank Binns <frank.binns@imgtec.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231124163917.300685-1-colin.i.king@gmail.com