kernel: mtd: parser: cmdline: Fix parsing of part-names with colons
Some devices (especially QCA ones) are already using hardcoded partition
names with colons in it. The OpenMesh A62 for example provides following
mtd relevant information via cmdline:
root=31:11 mtdparts=spi0.0:256k(0:SBL1),128k(0:MIBIB),384k(0:QSEE),64k(0:CDT),64k(0:DDRPARAMS),64k(0:APPSBLENV),512k(0:APPSBL),64k(0:ART),64k(custom),64k(0:KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive) rootfsname=rootfs rootwait
The change to split only on the last colon between mtd-id and partitions
will cause newpart to see following string for the first partition:
KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive)
Such a partition list cannot be parsed and thus the device fails to boot.
Avoid this behavior by making sure that the start of the first part-name
("(") will also be the last byte the mtd-id split algorithm is using for
its colon search.
Fixes: d6a9a92e3217 ("kernel: bump 5.4 to 5.4.69")
Signed-off-by: Sven Eckelmann <sven@narfation.org>