powerpc: add --bss-plt to LDFLAGS

With some versions of gcc (that we know of 4.6.3 and 4.8.2 are affected)
it is necessary to specify --bss-plt to get the final blrl in the
_GOT2_TABLE_. Without this the last symbol does not get it's address
relocated.  For the P2041RDB board this ended up being
NetArpWaitTimerStart which caused the ARP packets to timeout
immediately.

Signed-off-by: Joakim Tjernlund <joakim.tjernlund@transmode.se>
Signed-off-by: Chris Packham <judge.packham@gmail.com>
Acked-by: Joakim Tjernlund <joakim.tjernlund@transmode.se>
Acked-by: Scott Wood <scottwood@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>

arch/powerpc/config.mk

@@ -11,6 +11,7 @@ endif
 
 CONFIG_STANDALONE_LOAD_ADDR ?= 0x40000
 LDFLAGS_FINAL += --gc-sections
+LDFLAGS_FINAL += --bss-plt
 PLATFORM_RELFLAGS += -fpic -mrelocatable -ffunction-sections -fdata-sections \
 								-meabi
 PLATFORM_CPPFLAGS += -D__powerpc__ -ffixed-r2