drivers: gpu: Include appropriate header file in si_smc.c and remove prototype declaration from header file sislands_smc.h

Include header file gpu/drm/radeon/sislands_smc.h in drm/radeon/si_smc.c
because it uses function declared in the header file.

Remove prototype declaration of function si_set_smc_sram_address() from
drm/radeon/sislands_smc.h because the function is used only in one file
where it is declared static already.

This eliminates the following warnings in drm/radeon/si_smc.c:
drivers/gpu/drm/radeon/si_smc.c:46:5: warning: no previous prototype for ‘si_copy_bytes_to_smc’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:112:6: warning: no previous prototype for ‘si_start_smc’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:121:6: warning: no previous prototype for ‘si_reset_smc’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:135:5: warning: no previous prototype for ‘si_program_jump_on_start’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:142:6: warning: no previous prototype for ‘si_stop_smc_clock’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:151:6: warning: no previous prototype for ‘si_start_smc_clock’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:160:6: warning: no previous prototype for ‘si_is_smc_running’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:171:14: warning: no previous prototype for ‘si_send_msg_to_smc’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:192:14: warning: no previous prototype for ‘si_wait_for_smc_inactive’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:210:5: warning: no previous prototype for ‘si_load_smc_ucode’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:269:5: warning: no previous prototype for ‘si_read_smc_sram_dword’ [-Wmissing-prototypes]
drivers/gpu/drm/radeon/si_smc.c:284:5: warning: no previous prototype for ‘si_write_smc_sram_dword’ [-Wmissing-prototypes]
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>