bus: ti-sysc: Fix dispc quirk masking bool variables

Fix warning drivers/bus/ti-sysc.c:1806 sysc_quirk_dispc()
warn: masking a bool.

While at it let's add a comment for what were doing to make
the code a bit easier to follow.

Fixes: 7324a7a ("bus: ti-sysc: Implement display subsystem reset quirk")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-omap/a8ec8a68-9c2c-4076-bf47-09fccce7659f@kili.mountain/
Signed-off-by: Tony Lindgren <tony@atomide.com>

Author: tmlind

drivers/bus/ti-sysc.c

@@ -1791,7 +1791,7 @@ static u32 sysc_quirk_dispc(struct sysc *ddata, int dispc_offset,
 	if (!ddata->module_va)
 		return -EIO;
 
-	/* DISP_CONTROL */
+	/* DISP_CONTROL, shut down lcd and digit on disable if enabled */
 	val = sysc_read(ddata, dispc_offset + 0x40);
 	lcd_en = val & lcd_en_mask;
 	digit_en = val & digit_en_mask;
@@ -1803,7 +1803,7 @@ static u32 sysc_quirk_dispc(struct sysc *ddata, int dispc_offset,
 		else
 			irq_mask |= BIT(2) | BIT(3);	/* EVSYNC bits */
 	}
-	if (disable & (lcd_en | digit_en))
+	if (disable && (lcd_en || digit_en))
 		sysc_write(ddata, dispc_offset + 0x40,
 			   val & ~(lcd_en_mask | digit_en_mask));