SPEAr: Place ethaddr write and read within CONFIG_CMD_NET

ethaddr can be optionally read from i2c memory. So, chip_config command supports
reading/writing hw mac id into i2c memory. Placing this code within
CONFIG_CMD_NET as this would only be needed when network interface is configured

Signed-off-by: Vipin Kumar <vipin.kumar@st.com>
Signed-off-by: Amit Virdi <amit.virdi@st.com>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/doc/README.spear b/doc/README.spear
index a8b1052..a6ff7fd 100644
--- a/doc/README.spear
+++ b/doc/README.spear
@@ -46,3 +46,11 @@
 	make FLASH=PNOR (supported by SPEAr310 and SPEAr320)
 	- This option generates a uboot image that supports emi controller for
 	CFI compliant parallel NOR flash
+
+Mac id storage and retrieval in spear platforms
+
+Please read doc/README.enetaddr for the implementation guidelines for mac id
+usage. Basically, environment has precedence over board specific storage. The
+ethaddr beeing used for the network interface is always taken only from
+environment variables. Although, we can check the mac id programmed in i2c
+memory by using chip_config command