configs: j7200_evm_a72: Add CONFIG_PREBOOT to configure ethernet PHY

Add CONFIG_PREBOOT to provide an automatic and easier way
to configure ethernet PHY before loading the firmware.
Signed-off-by: NKishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: NLokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210721155849.20994-19-kishon@ti.com

configs/j7200_evm_a72_defconfig

@@ -30,6 +30,7 @@ CONFIG_SPL_LOAD_FIT=y
 CONFIG_SPL_LOAD_FIT_ADDRESS=0x81000000
 # CONFIG_USE_SPL_FIT_GENERATOR is not set
 CONFIG_OF_BOARD_SETUP=y
+CONFIG_PREBOOT="run main_cpsw0_qsgmii_phyinit;"
 CONFIG_BOOTCOMMAND="run findfdt; run envboot; run init_${boot}; run boot_rprocs; run get_kern_${boot}; run get_fdt_${boot}; run get_overlay_${boot}; run run_kern"
 CONFIG_LOGLEVEL=7
 CONFIG_SPL_BOARD_INIT=y