Staging: bcm: Outsourced cmd handling to function

This patch outsourced the true-branch for the IOCTL_BCM_NVM_READ command
handling to shorten the bcm_char_ioctl_nvm_rw() function.

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>