drm/amdgpu: Add missing offsets in gc_11_0_0_offset.h

IB1 registers:
regCP_IB1_CMD_BUFSZ
regCP_IB1_BASE_LO
regCP_IB1_BASE_HI
regCP_IB1_BUFSZ
regCP_MES_DEBUG_INTERRUPT_INSTR_PNTR

Above registers are part of the asic but not of
the offset file for gc_11_0_0_offset.h and hence
adding them.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>