imx8mq_evk: README: Make the underline marker fill the whole sentence

Let the underline marker "=" fill the whole sentence for better
readability.

Signed-off-by: Fabio Estevam <festevam@gmail.com>

board/freescale/imx8mq_evk/README

@@ -1,14 +1,14 @@
 U-Boot for the NXP i.MX8MQ EVK board
 
 Quick Start
-====================
+===========
 - Build the ARM Trusted firmware binary
 - Get ddr and hdmi fimware
 - Build U-Boot
 - Boot
 
 Get and Build the ARM Trusted firmware
-====================
+======================================
 Note: srctree is U-Boot source directory
 Get ATF from: https://source.codeaurora.org/external/imx/imx-atf
 branch: imx_4.14.62_1.0.0_beta
@@ -16,7 +16,7 @@ $ make PLAT=imx8mq bl31
 $ cp build/imx8mq/release/bl31.bin $(srctree)
 
 Get the ddr and hdmi firmware
-====================
+=============================
 $ wget https://www.nxp.com/lgfiles/NMG/MAD/YOCTO/firmware-imx-7.9.bin
 $ chmod +x firmware-imx-7.9.bin
 $ ./firmware-imx-7.9.bin
@@ -24,7 +24,7 @@ $ cp firmware-imx-7.9/firmware/hdmi/cadence/signed_hdmi_imx8m.bin $(srctree)
 $ cp firmware-imx-7.9/firmware/ddr/synopsys/lpddr4*.bin $(srctree)
 
 Build U-Boot
-====================
+============
 $ export CROSS_COMPILE=aarch64-poky-linux-
 $ make imx8mq_evk_defconfig
 $ make flash.bin
@@ -33,5 +33,5 @@ Burn the flash.bin to MicroSD card offset 33KB
 $sudo dd if=flash.bin of=/dev/sd[x] bs=1024 seek=33
 
 Boot
-====================
+====
 Set Boot switch SW801: 1100 and Bmode: 10 to boot from Micro SD.