This reads to stdout, in binary format. With "-v" it prints text and
scans the bus too. The examples here below use the same card (and same
data) as in commit "d44ace7e

 w1: complete eeprom low-level support".

   spusa.root# ./tools/wrpc-w1-read -b 2 0 5 | od -t u1 -Ax -w1
   000000  40
   000001  41
   000002  42
   000003 243
   000004 244

   spusa.root# ./tools/wrpc-w1-read -v -b 2 30 6
   ./ohwr/wrpc-sw/tools/wrpc-w1-read: found device 10dc:018d: 0000:02:00.0
   ./ohwr/wrpc-sw/tools/wrpc-w1-read: found device 10dc:018d: 0000:04:00.0
   device 0: 68000801dce56910
   device 1: 5b0000036c567628
   device 2: f70000001eda8242
   device 3: 5f00000040e50143
   Reading device on bus 2: offset 30 (0x1e), len 6
   offset   30 (0x01e):  11 (0x0b)
   offset   31 (0x01f):  22 (0x16)
   offset   32 (0x020):  33 (0x21)
   offset   33 (0x021):  44 (0x2c)
   offset   34 (0x022):  55 (0x37)
   offset   35 (0x023):  66 (0x42)

Signed-off-by: Alessandro Rubini <rubini@gnudd.com>