mb/google/poppy: Rework OV5670 power on sequence

In particular:

- Enable regulators *after* configuring the voltage

- Allow 1 ms for the voltages to settle

- Enable clock after powering on regulators

- Remove extra delays between enabling things. The sensor requires 8192
  clock cycles after the reset is lifted before I²C access, so 1 ms is
  enough.

- Make the delay after lifting xshutdown 10 ms. This guarantees that
  streaming will only start once the sensor has had enough time to settle
  after lifting the reset.

BUG=chromium:959232

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: Jacopo Mondi <jacopo@jmondi.org>
Change-Id: I4589a7d7ec324f4520572a406cc11ad3feec8b21
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36723
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/mainboard/google/poppy/variants/baseboard/include/baseboard/acpi/camera_pmic.asl

@@ -526,30 +526,39 @@ Scope (\_SB.PCI0.I2C2)
 						daisy chain */
 						DOVD(1)
 
-						VAX2 = 1 /* Enable VAUX2 */
-
 						if (LNotEqual (AX2V, 52)) {
 							/* Set VAUX2 as
 							1.8006 V */
 							AX2V = 52
 						}
+						VAX2 = 1 /* Enable VAUX2 */
+
+						\_SB.PCI0.I2C2.PMIC.CGP4(1)
+
+						/*
+						 * Wait for DOVDD and AVDD
+						 * to settle.
+						 */
+						Sleep(1)
+
+						if (LNotEqual (AX1V, 19)) {
+						/* Set VAUX1 as 1.2132V */
+							AX1V = 19
+						}
+						VAX1 = 1 /* Enable VAUX1 */
+
+						/* Wait for VDD to settle. */
 						Sleep(1)
 
 						\_SB.PCI0.I2C2.PMIC.CLKE()
 						CLE1 = 1
 
-						VAX1 = 1 /* Enable VAUX1 */
-						if (LNotEqual (AX1V, 19)) {
-						/* Set VAUX1 as 1.2132V */
-							AX1V = 19
-						}
-						Sleep(3)
-
-						\_SB.PCI0.I2C2.PMIC.CGP4(1)
-						Sleep(3)
-
 						\_SB.PCI0.I2C2.PMIC.CGP5(1)
-						Sleep(3)
+						/*
+						 * Ensure 10 ms between
+						 * power-up and streamon.
+						 */
+						Sleep(10)
 						STA = 1
 					}
 				}