Coccinelle: Move err_cast.cocci to the api directory

Signed-off-by: Nicolas Palix <npalix@diku.dk>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Michal Marek <mmarek@suse.cz>

diff --git a/scripts/coccinelle/err_cast.cocci b/scripts/coccinelle/api/err_cast.cocci
similarity index 100%
rename from scripts/coccinelle/err_cast.cocci
rename to scripts/coccinelle/api/err_cast.cocci