meta-ibm: Increase the BMC dump total size

Set the BMC dump total allowed size as 409600KB.
p10bmc machines have an emmc based filesystem so therefore can fit more
bmc dumps.

Signed-off-by: Dhruvaraj Subhashchandran <dhruvaraj@in.ibm.com>
Change-Id: I05c1626ce9a03685adfdfd9713b3053ae8e63737
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>