mx6qsabrelite: README: No need to pass 'u-boot.imx'

The u-boot.imx binary is generated by default, so no need to pass it in the
'make' line.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/board/freescale/mx6qsabrelite/README b/board/freescale/mx6qsabrelite/README
index 6f2f534..7458ff3 100644
--- a/board/freescale/mx6qsabrelite/README
+++ b/board/freescale/mx6qsabrelite/README
@@ -63,7 +63,7 @@
 To build U-Boot for the SabreLite board:
 
  make mx6qsabrelite_config
- make u-boot.imx
+ make
 
 To copy the resulting u-boot.imx to the SD card: