drm/amdgpu: remove always false comparison in 'amdgpu_atombios_i2c_process_i2c_ch'

Fixes gcc '-Wtype-limits' warning:

drivers/gpu/drm/amd/amdgpu/atombios_i2c.c: In function
‘amdgpu_atombios_i2c_process_i2c_ch’:
drivers/gpu/drm/amd/amdgpu/atombios_i2c.c:79:11: warning: comparison is
always false due to limited range of data type [-Wtype-limits]

'num' is 'u8', so it will never be greater than 'TOM_MAX_HW_I2C_READ',
which is defined as 255. Therefore, the comparison can be removed.

Fixes: d38ceaf99ed0 ("drm/amdgpu: add core driver (v4)")
Signed-off-by: yu kuai <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/atombios_i2c.c

···
 		}
 		args.lpI2CDataOut = cpu_to_le16(out);
 	} else {
-		if (num > ATOM_MAX_HW_I2C_READ) {
-			DRM_ERROR("hw i2c: tried to read too many bytes (%d vs 255)\n", num);
-			r = -EINVAL;
-			goto done;
-		}
 		args.ucRegIndex = 0;
 		args.lpI2CDataOut = 0;
 	}