arm: dts: ti: omap: Fixup pinheader typo

This commit fixes a typo introduced in commit
ee368a1 ("ARM: dts: am335x-boneblack.dts: unique gpio-line-names").
gpio0_7 is located on the P9 header on the BBB.
This was verified with a BeagleBone Black by toggling the pin and
checking with a multimeter that it corresponds to pin 42 on the P9
header.

Signed-off-by: Albin Törnqvist <albin.tornqvist@codiax.se>
Link: https://lore.kernel.org/r/20250624114839.1465115-2-albin.tornqvist@codiax.se
Fixes: ee368a1 ("ARM: dts: am335x-boneblack.dts: unique gpio-line-names")
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

Author: Albin Törnqvist

arch/arm/boot/dts/ti/omap/am335x-boneblack.dts

@@ -35,7 +35,7 @@
 		"P9_18 [spi0_d1]",
 		"P9_17 [spi0_cs0]",
 		"[mmc0_cd]",
-		"P8_42A [ecappwm0]",
+		"P9_42A [ecappwm0]",
 		"P8_35 [lcd d12]",
 		"P8_33 [lcd d13]",
 		"P8_31 [lcd d14]",