drm/radeon: change cayman_default_state table from global to static

cayman_default_state and cayman_default_size are only
used in ni.c.  Single file symbols should be static.
So move their definitions to cayman_blit_shaders.h
and change their storage-class-specifier to static.

Remove unneeded cayman_blit_shader.c

cayman_ps/vs definitions were removed with
commit 4f862967 ("drm/radeon/kms: remove r6xx+ blit copy routines")
So their declarations in cayman_blit_shader.h
are not needed, so remove them.

Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>