drm/amd/display: Change parameters to fix certain compiler errors

[Why]
String literals must be assigned to const char pointers.

[How]
By adding const keyword to fix compilation errors.

Reviewed-by: Lohita Mudimela <lohita.mudimela@amd.com>
Signed-off-by: Revalla Hari Krishna <Harikrishna.Revalla@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Revalla Hari Krishna

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer_debug.c

@@ -46,7 +46,7 @@
 #include "clk_mgr.h"
 
 __printf(3, 4)
-unsigned int snprintf_count(char *pbuf, unsigned int bufsize, char *fmt, ...)
+unsigned int snprintf_count(char *pbuf, unsigned int bufsize, const char *fmt, ...)
 {
 	int ret_vsnprintf;
 	unsigned int chars_printed;

drivers/gpu/drm/amd/display/dc/dm_services.h

@@ -143,7 +143,7 @@ void generic_reg_wait(const struct dc_context *ctx,
 	unsigned int delay_between_poll_us, unsigned int time_out_num_tries,
 	const char *func_name, int line);
 
-unsigned int snprintf_count(char *pBuf, unsigned int bufSize, char *fmt, ...);
+unsigned int snprintf_count(char *pBuf, unsigned int bufSize, const char *fmt, ...);
 
 /* These macros need to be used with soc15 registers in order to retrieve
  * the actual offset.