staging: comedi: addi_apci_3120: cleanup apci3120_detach()

This driver always tried to allocate the dma buffers so they need to
be free'd when the board is detached.

Remove the unneeded tests for the eeprom chip and bring the code
back an indent.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>