lmb: Increase the default number of regions to 64

In modern use cases, limiting ourselves to 8 regions is simply too few.
A few platforms already had been working around this by increasing the
default to 64. Increase this limit globally to 64.

Link: https://stackoverflow.com/questions/75232382/u-boot-fails-with-reading-file-would-overwrite-reserve-memory-on-raspberry-cm4


Signed-off-by: Tom Rini <trini@konsulko.com>