ehea: fix mutex and spinlock use

  Looks like to me that the ehea_fw_handles.lock mutex and the
ehea_bcmc_regs.lock spinlock are taken much longer than necessary and could
as well be pushed inside the functions that need them
(ehea_update_firmware_handles() and ehea_update_bcmc_registrations())
rather than at each callsite.

Signed-off-by: Sebastien Dugue <sebastien.dugue@bull.net>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>