package/elf2flt: hide when an MMU is used

elf2flt is specifically for cases where an MMU is not available.
There is no point in building elf2flt when using an MMU.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/elf2flt/Config.in.host

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_HOST_ELF2FLT
 	bool "Enable elf2flt support?"
 	depends on BR2_arm || BR2_bfin || BR2_sh || BR2_sparc
+	depends on !BR2_USE_MMU
 	help
 	  uCLinux uses a Binary Flat format commonly known as BFLT. It
 	  is a relatively simple and lightweight executable format