drm/amdgpu: fix a signedness bug in __verify_ras_table_checksum()

If amdgpu_eeprom_read() returns a negative error code then the error
handling checks:

	if (res < buf_size) {

The problem is that "buf_size" is a u32 so negative values are type
promoted to a high positive values and the condition is false.  Fix
this by changing the type of "buf_size" to int.

Fixes: 63d4c081 ("drm/amdgpu: Optimize EEPROM RAS table I/O")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ras_eeprom.c

@@ -978,9 +978,8 @@ const struct file_operations amdgpu_ras_debugfs_eeprom_table_ops = {
 static int __verify_ras_table_checksum(struct amdgpu_ras_eeprom_control *control)
 {
 	struct amdgpu_device *adev = to_amdgpu_device(control);
-	int res;
+	int buf_size, res;
 	u8  csum, *buf, *pp;
-	u32 buf_size;
 
 	buf_size = RAS_TABLE_HEADER_SIZE +
 		control->ras_num_recs * RAS_TABLE_RECORD_SIZE;