ARM: davinci: make I2C support optional

ARM: davinci: make I2C support optional

The davinci platform has tried to get support for the EEPROM right,
but failed to get a clean build so far. At the moment, we get
a warning whenever CONFIG_SYSFS is disabled, as that is needed by
EEPROM_AT24:

warning: (MACH_DAVINCI_EVM && MACH_SFFSDR && MACH_DAVINCI_DM6467_EVM && MACH_DAVINCI_DM365_EVM && MACH_DAVINCI_DA830_EVM && MACH_MITYOMAPL138 && MACH_MINI2440) selects EEPROM_AT24 which has unmet direct dependencies (I2C && SYSFS)

Kevin Hilman initially added the 'select' to ensure that EEPROM_AT24
is always enabled in machines that really want it for normal operation
(i.e. for reading the MAC address). This broke when I2C was disabled,
and Russell King followed up with another patch to select that as
well.

I now see that the SYSFS dependency is still missing, which leaves
us with three options:

a) add 'select SYSFS' in addition to the others
b) change AT24_EEPPROM to work without sysfs (should be possible)
c) remove all those selects again and get the files to build when
   I2C is disabled.

I would really hate to do a) because adding select statements that
hardwire user-selectable symbols is generally a bad idea. I first
tried b) but then ended up redoing the patch from scratch to approach
c), so we can also remove the other selects.

I checked that CONFIG_I2C is still enabled with davinci_all_defconfig,
so that does not have to change.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 45b146d746ea ("ARM: Davinci: Fix I2C build errors")
Fixes: 22ca466847ad ("davinci: kconfig: select at24 eeprom for selected boards")
Signed-off-by: Sekhar Nori <nsekhar@ti.com>