ipq806x: remove transition workarounds for qcom-smem partitions

ipq806x: remove transition workarounds for qcom-smem partitions

The out-of-tree qcom-smem patches traditionally displayed mtd partition names
in upper case, starting with the new mainline qcom-smem support in kernel v5.10,
it switched to normalizing the partition names to lower case.

While both 5.4 and 5.10 were supported in the target, we carried a workaround
to support both of them. Since the target has dropped 5.4 recently, those
can be removed now.

Ref:

2db9dded0a1a ("ipq806x: nbg6817: case-insensitive qcom-smem partitions")
435dc2e77e3b ("ipq806x: ecw5410: case-insensitive qcom-smem partitions")
f70e11cd974e ("ipq806x: g10: case-insensitive qcom-smem partitions")

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>