scripts: add mxsimage tool

This is copied from U-Boot v2014.10 and modified for use with
barebox:

- Add a main() function to make it a standalone tool
- Add option to pass in the prepare stage and bootloader
  image as options. If the config file contains @PREP@ or
  @BOOTLOADER@ the string will be replaced with the actual
  image file passed via the -p and -b options.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

scripts/.gitignore

@@ -22,3 +22,4 @@ bareboximd-target
 bareboxstate
 bareboxstate-target
 mk-am35xx-spi-image
+mxsimage

scripts/Makefile

@@ -19,6 +19,8 @@ hostprogs-$(CONFIG_ARCH_S5PCxx)  += s5p_cksum
 hostprogs-$(CONFIG_ARCH_DAVINCI) += mkublheader
 hostprogs-$(CONFIG_ARCH_ZYNQ)	 += zynq_mkimage
 hostprogs-$(CONFIG_ARCH_SOCFPGA) += socfpga_mkimage
+hostprogs-$(CONFIG_ARCH_MXS)     += mxsimage
+HOSTLOADLIBES_mxsimage  = `pkg-config --libs openssl`
 
 subdir-y			+= mod
 subdir-$(CONFIG_OMAP4_USBBOOT)	+= omap4_usbboot