Input: elantech - enable 3rd button support on Fujitsu CELSIUS H780

Like Fujitsu CELSIUS H760, the H780 also has a three-button Elantech
touchpad, but the driver needs to be told so to enable the middle touchpad
button.

The elantech_dmi_force_crc_enabled quirk was not necessary with the H780.

Also document the fw_version and caps values detected for both H760 and
H780 models.
Signed-off-by: Matti Kurkela <Matti.Kurkela@iki.fi>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/elantech.c

@@ -1119,6 +1119,8 @@ static int elantech_get_resolution_v4(struct psmouse *psmouse,
  * Asus UX31               0x361f00        20, 15, 0e      clickpad
  * Asus UX32VD             0x361f02        00, 15, 0e      clickpad
  * Avatar AVIU-145A2       0x361f00        ?               clickpad
+ * Fujitsu CELSIUS H760    0x570f02        40, 14, 0c      3 hw buttons (**)
+ * Fujitsu CELSIUS H780    0x5d0f02        41, 16, 0d      3 hw buttons (**)
  * Fujitsu LIFEBOOK E544   0x470f00        d0, 12, 09      2 hw buttons
  * Fujitsu LIFEBOOK E546   0x470f00        50, 12, 09      2 hw buttons
  * Fujitsu LIFEBOOK E547   0x470f00        50, 12, 09      2 hw buttons
@@ -1171,6 +1173,13 @@ static const struct dmi_system_id elantech_dmi_has_middle_button[] = {
 			DMI_MATCH(DMI_PRODUCT_NAME, "CELSIUS H760"),
 		},
 	},
+	{
+		/* Fujitsu H780 also has a middle button */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "CELSIUS H780"),
+		},
+	},
 #endif
 	{ }
 };