mediatek: fix broken PCIe caused by update to 5.15.158

mediatek: fix broken PCIe caused by update to 5.15.158

The patch "710-pci-pcie-mediatek-add-support-for-coherent-DMA.patch"
makes use of "syscon_regmap_lookup_by_phandle" which requires that
"syscon" be in the compatible list.

Without this patch, PCIe probe will fail with the following error:

[    1.287467] mtk-pcie 1a143000.pcie: host bridge /pcie@1a143000 ranges:
[    1.294019] mtk-pcie 1a143000.pcie: Parsing ranges property...
[    1.299901] mtk-pcie 1a143000.pcie:      MEM 0x0020000000..0x0027ffffff -> 0x0020000000
[    1.307954] mtk-pcie 1a143000.pcie: missing hifsys node
[    1.313185] mtk-pcie: probe of 1a143000.pcie failed with error -22

Fixes: 01c58a0d2a ("kernel: bump 5.15 to 5.15.158")
Signed-off-by: Rany Hany <rany_hany@riseup.net>
(cherry picked from commit 8607372b410fbb24b08de97ff5941341d0870d6f)