Use ARM TLS register for emulator

This is dependent on having a kernel that uses CONFIG_HAS_TLS_REG=y
which is enabled in change Ic497e41270a4ad78ca55ab5674b5342e8d939e56

Change-Id: I456c270dd5b4d8fedfb423ac8e363fd37b77f8ce
diff --git a/target/board/generic/BoardConfig.mk b/target/board/generic/BoardConfig.mk
index 229ea9c..b3763c5 100644
--- a/target/board/generic/BoardConfig.mk
+++ b/target/board/generic/BoardConfig.mk
@@ -21,6 +21,7 @@
 TARGET_ARCH_VARIANT := armv7-a
 TARGET_CPU_ABI := armeabi-v7a
 TARGET_CPU_ABI2 := armeabi
+ARCH_ARM_HAVE_TLS_REGISTER := true
 
 HAVE_HTC_AUDIO_DRIVER := true
 BOARD_USES_GENERIC_AUDIO := true