mtd: remove the warning about read-only caused by size vs. block boundary mismatch

Since the kernel/rootfs split handling was modified 2 years ago by r37283 (
https://dev.openwrt.org/changeset/37283

 ) and by the subsequent checkins,
users have seen rather scary mtd errors in the log at every boot. The message
ends "-- forcing read-only", which looks a bit error-like. That error has
been mentioned in some forum threads, when users have noticed this message
instead of some actual error.

[    2.940000] 0x000000070000-0x000000ff0000 : "firmware"
[    2.970000] 2 netgear-fw partitions found on MTD device firmware
[    2.970000] 0x000000070000-0x000000188440 : "kernel"
[    2.980000] mtd: partition "kernel" must either start or end on erase
block boundary or be smaller than an erase block -- forcing read-only
[    2.990000] 0x000000188440-0x000000ff0000 : "rootfs"

The patch removes the rather useless warning message.

signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>

SVN-Revision: 45669