bt: Remove B_BUSY state
bt: Remove B_BUSY state

The bt layer used to cache the value of B_BUSY in the state machine,
assuming that once B_BUSY was cleared by the BMC that it would never
be set by the BMC again unless a message was sent to the bt interface.

This was mostly true for the AMI firmware except when the BMC reboots
which causes B_BUSY to be set. There may also be additional
circumstances which set B_BUSY. Therefore the bt layer must check
B_BUSY is clear before sending a message making the B_BUSY state
superfluous.

Signed-off-by: Alistair Popple <e9adbcf81c8a36ccc628e09bc92d0e25e1c8e501@popple.id.au>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

shenki/skiboot,csmart/skiboot,qemu/skiboot,open-power/skiboot,qemu/skiboot,legoater/skiboot,csmart/skiboot,mikey/skiboot,open-power/skiboot,mikey/skiboot,shenki/skiboot,shenki/skiboot,qemu/skiboot,ddstreet/skiboot,stewart-ibm/skiboot,ddstreet/skiboot,apopple/skiboot,legoater/skiboot,shenki/skiboot,apopple/skiboot,csmart/skiboot,stewart-ibm/skiboot,apopple/skiboot,open-power/skiboot,legoater/skiboot,qemu/skiboot,qemu/skiboot,legoater/skiboot,ddstreet/skiboot,mikey/skiboot,shenki/skiboot,open-power/skiboot,legoater/skiboot,open-power/skiboot,stewart-ibm/skiboot