mb/google/brya/acpi: Poll more frequently in GPPL

The full dGPU power-on sequence, when executed from ACPI, is taking
roughly 15ms or so, which puts it close to the maximum of 20ms required
from the Nvidia spec. Changing the polling period to 100 us instead of 1
ms drastically reduces the time required for this sequence, now taking
typically 7 ms or so. This gives a lot more margin during the power on
sequence.

BUG=b:238466724
TEST=Sequence verified by EE on a scope

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Change-Id: I3ba676c5fac983a0c1ad1d60c3863d06ed33fa27
Reviewed-on: https://review.coreboot.org/c/coreboot/+/66020
Reviewed-by: Subrata Banik <subratabanik@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>

src/mainboard/google/brya/acpi/utility.asl

@@ -9,14 +9,15 @@
 Method (GPPL, 3, Serialized)
 {
 	Local0 = 0
-	While (Local0 < Arg2)
+	Local1 = Arg2 * 10
+	While (Local0 < Local1)
 	{
 		If (\_SB.PCI0.GRXS (Arg0) == Arg1) {
 			Return (0)
 		} Else {
 			Local0++
 		}
-		Sleep (1)
+		Stall (100)
 	}
 
 	If (Local0 == Arg2) {