powerpc/mm: Remove __this_fixmap_does_not_exist()

This function has not been used since commit 9494a1e8428ea
("powerpc: use generic fixmap.h)

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
1 file changed