arch: FDPIC is not supported on m68k

The current binfmt selection in arch/Config.in allows to select FDPIC
on m68k, which is incorrect. This commit fixes that, and makes sure
FDPIC is the default on Blackfin, while FLAT is the default on m68k.

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

arch/Config.in

@@ -255,7 +255,8 @@ config BR2_ARCH_HAS_ATOMICS
 choice
 	prompt "Target Binary Format"
 	depends on BR2_bfin || BR2_m68k
-	default BR2_BINFMT_FDPIC
+	default BR2_BINFMT_FDPIC if BR2_bfin
+	default BR2_BINFMT_FLAT if BR2_m68k
 
 config BR2_BINFMT_ELF
 	bool "ELF"
@@ -267,7 +268,7 @@ config BR2_BINFMT_ELF
 
 config BR2_BINFMT_FDPIC
 	bool "FDPIC"
-	depends on BR2_bfin || BR2_m68k
+	depends on BR2_bfin
 	help
 	  ELF FDPIC binaries are based on ELF, but allow the individual load
 	  segments of a binary to be located in memory independently of each