media: atomisp: get rid of two unused functions

Those cause build to break with -Werror with clang-12:

	drivers/staging/media/atomisp/pci/hive_isp_css_common/host/gdc.c:121:24: error: unused function 'gdc_reg_load' [-Werror,-Wunused-function]
	drivers/staging/media/atomisp/pci/isp/kernels/raw/raw_1.0/ia_css_raw.host.c:33:1: error: unused function 'sh_css_elems_bytes_from_info' [-Werror,-Wunused-function]

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>