uboot-omap: enable thumb for overo

Even it's unknown if it's booting with thumb, because the lack of hardware.
Enable it for now, so the build succeed, because without thumb it can not fit
into spl.

Signed-off-by: Alexander Couzens <lynxis@fe80.eu>

package/boot/uboot-omap/patches/104-omap3-overo-enable-thumb.patch

@@ -0,0 +1,18 @@
+Index: u-boot-2017.01/include/configs/omap3_overo.h
+===================================================================
+--- u-boot-2017.01.orig/include/configs/omap3_overo.h
++++ u-boot-2017.01/include/configs/omap3_overo.h
+@@ -11,6 +11,13 @@
+ #define CONFIG_NAND
+ 
+ #include <configs/ti_omap3_common.h>
++
++/* try to enable thumb - unknown if it's working
++ * but otherwise it's too big for spl */
++#ifndef CONFIG_SYS_THUMB_BUILD
++#define CONFIG_SYS_THUMB_BUILD
++#endif
++
+ /*
+  * We are only ever GP parts and will utilize all of the "downloaded image"
+  * area in SRAM which starts at 0x40200000 and ends at 0x4020FFFF (64KB).