Remove a redundant node from the Pine64 Pinebook Pro dts, which is intended
to provide a value for the delay in PCI Express enumeration, but that isn't
supported without additional out-of-tree kernel patches.

There were already efforts to upstream those kernel patches, because they
reportedly make some PCI Express cards (such as LSI SAS HBAs) usable in
Pine64 RockPro64 (which is also based on the RK3399);  otherwise, those PCI
Express cards fail to enumerate.  However, providing the required background
and explanations proved to be a tough nut to crack, which is the reason why
those patches remain outside of the kernel mainline for now.

If those out-of-tree patches eventually become upstreamed, the resulting
device-tree changes will almost surely belong to the RK3399 SoC dtsi.  Also,
the above-mentioned unusable-without-out-of-tree-patches PCI Express devices
are in all fairness not usable in a Pinebook Pro without some extensive
hardware modifications, which is another reason to delete this redundant
node.  When it comes to the Pinebook Pro, only M.2 NVMe SSDs can be installed
out of the box (using an additional passive adapter PCB sold separately by
Pine64), which reportedly works fine with no additional patches.

Fixes: 5a65505a ("arm64: dts: rockchip: Add initial support for Pinebook Pro")
Signed-off-by: Dragan Simic <dsimic@manjaro.org>
Link: https://lore.kernel.org/r/0f82c3f97cb798d012270d13b34d8d15305ef293.1711923520.git.dsimic@manjaro.orgSigned-off-by: Heiko Stuebner <heiko@sntech.de>