media: staging: atomisp: don't declare the same vars as both private and public

media: staging: atomisp: don't declare the same vars as both private and public

The mmu_private.h header is included at mmu.c, with duplicates the
already existing definitions at mmu_public.h.

Fix this by removing the erroneous header file.

Solve those issues:

    drivers/staging/media/atomisp/pci/atomisp2/css2400/hive_isp_css_common/host/mmu_private.h:24:26: warning: function 'mmu_reg_store' with external linkage has definition
    drivers/staging/media/atomisp/pci/atomisp2/css2400/hive_isp_css_common/host/mmu_private.h:35:30: warning: function 'mmu_reg_load' with external linkage has definition
    drivers/staging/media/atomisp/pci/atomisp2/css2400/hive_isp_css_common/host/mmu_private.h:24:26: warning: function 'mmu_reg_store' with external linkage has definition
    drivers/staging/media/atomisp/pci/atomisp2/css2400/hive_isp_css_common/host/mmu_private.h:35:30: warning: function 'mmu_reg_load' with external linkage has definition

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>