ARM: bcm2835: fix mailbox timeout

My original intention was to have a 100ms timeout. However, the timer
operations used return values in ms not us, so we ended up with a 100s
timeout instead. Fixing this exposes that some operations need longer
to operate than 100ms, so bump the timeout up to a whole second.

Reported-by: Andre Heider <a.heider@gmail.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>