firewire: test: add test of device attributes for simple AV/C device

At present, core function can handle node which has configuration ROM
similar to standard AV/C device somehow. The standard layout of
configuration ROM is described in the following document.

- Configuration ROM for AV/C Devices 1.0 (Dec. 12, 2000, 1394 Trading
  Association)

This commit adds a KUnit test for the above case.

The following output is the parse result for the hard-coded data, by
config-rom-pretty-printer in linux-firewire-utils
(https://git.kernel.org/pub/scm/utils/ieee1394/linux-firewire-utils.git/).

$ config-rom-pretty-printer < /tmp/rom.img
               ROM header and bus information block
               -----------------------------------------------------------------
1024  0404eabf  bus_info_length 4, crc_length 4, crc 60095
1028  31333934  bus_name "1394"
1032  e0646102  irmc 1, cmc 1, isc 1, bmc 0, cyc_clk_acc 100, max_rec 6 (128)
1036  ffffffff  company_id ffffff     |
1040  ffffffff  device_id 1099511627775  | EUI-64 18446744073709551615

               root directory
               -----------------------------------------------------------------
1044  00063287  directory_length 6, crc 12935
1048  03ffffff  vendor
1052  8100000a  --> descriptor leaf at 1092
1056  17ffffff  model
1060  8100000e  --> descriptor leaf at 1116
1064  0c0083c0  node capabilities: per IEEE 1394
1068  d1000001  --> unit directory at 1072

               unit directory at 1072
               -----------------------------------------------------------------
1072  0004442d  directory_length 4, crc 17453
1076  1200a02d  specifier id
1080  13010001  version
1084  17ffffff  model
1088  81000007  --> descriptor leaf at 1116

               descriptor leaf at 1092
               -----------------------------------------------------------------
1092  0005c915  leaf_length 5, crc 51477
1096  00000000  textual descriptor
1100  00000000  minimal ASCII
1104  56656e64  "Vend"
1108  6f72204e  "or N"
1112  616d6500  "ame"

               descriptor leaf at 1116
               -----------------------------------------------------------------
1116  00057f16  leaf_length 5, crc 32534
1120  00000000  textual descriptor
1124  00000000  minimal ASCII
1128  4d6f6465  "Mode"
1132  6c204e61  "l Na"
1136  6d650000  "me"

Link: https://lore.kernel.org/r/20231221134849.603857-5-o-takashi@sakamocchi.jp


Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>