arm: dts: ti: omap: Fixup pinheader typo

This commit fixes a typo introduced in commit
ee368a10 ("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: ee368a10 ("ARM: dts: am335x-boneblack.dts: unique gpio-line-names")
Signed-off-by: Kevin Hilman <khilman@baylibre.com>