drm: kernel-doc: drm_dp_helper.h: fix a typo

Right now, kernel-doc generates a warning:
	./include/drm/drm_dp_helper.h:1786: warning: Function parameter or member 'hbr2_reset' not described in 'drm_dp_phy_test_params'

This is due to a typo:

	@hb2_reset -> @hbr2_reset
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/2a615cb38e951215bb1bddc2481ad323c9cf3fc9.1603791716.git.mchehab+huawei@kernel.org

include/drm/drm_dp_helper.h

@@ -1836,7 +1836,7 @@ static inline void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
  * @link_rate: Requested Link rate from DPCD 0x219
  * @num_lanes: Number of lanes requested by sing through DPCD 0x220
  * @phy_pattern: DP Phy test pattern from DPCD 0x248
- * @hb2_reset: DP HBR2_COMPLIANCE_SCRAMBLER_RESET from DCPD 0x24A and 0x24B
+ * @hbr2_reset: DP HBR2_COMPLIANCE_SCRAMBLER_RESET from DCPD 0x24A and 0x24B
  * @custom80: DP Test_80BIT_CUSTOM_PATTERN from DPCDs 0x250 through 0x259
  * @enhanced_frame_cap: flag for enhanced frame capability.
  */