i2c_eeprom: Add reading support

This patch implements the reading functionality for the generic I2C
EEPROM driver, which was just a non-functional stub until now.

Since the page size will be of importance for the writing support, we
add suitable members to the private data structure to keep track of it.

Compatibility strings for a range of at24c* chips are added.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 2373037..b84e351 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -144,4 +144,9 @@
 	  Hidden option to enable QEMU fw_cfg interface. This will be selected by
 	  either CONFIG_CMD_QFW or CONFIG_GENERATE_ACPI_TABLE.
 
+config I2C_EEPROM
+	bool "Enable driver for generic I2C-attached EEPROMs"
+	depends on MISC
+	help
+	  Enable a generic driver for EEPROMs attached via I2C.
 endmenu