i2c: increase BUFLEN/CMDLEN to 128, add page flag.

128 byte reads are much more common than 32 byte reads. The message
passing + setup/teardown for a read is much more expensive, in terms
of time, than the reading itself. A slightly bigger struct is well
worth the time savings. This reduces read times for /dev/eeprom
from 57 seconds per 4KB to 14 seconds.

Additionally, make sending the page address in the eeprom driver
and utility optional. This can save a little time when reading
within the same page and allows support for smaller devices that
don't support pages (example: chips containing EDID).

Change-Id: Ie48087caee40c11fa241d1555fce9309ddd27b43