tplink-safeloader: increase kernel partition for CPE/WBSx10v1

tplink-safeloader: increase kernel partition for CPE/WBSx10v1

This is a preparation for ath79 support of the CPE210/CPE510 v1.
Kernel size is chosen equal to the latest update for CPE610 v1.

This also updates the partition size in ar71xx target, so code
remains consistent if someone looks up the device. Since CPE210,
CPE510, WBS210 and WBS510 (all v1) share the same partition
layout definition, and are on deprecated target anyway, this
changes them all at once.

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