Commit 
181bd9dc61d2da88b78f1c1138a685dae39354d6 introduced Kconfig selection
for SYS_PROMPT. When applying the new picosam9g45 board this change slipped
through, adopt it.
Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
 CONFIG_TARGET_PICOSAM9G45=y
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="AT91SAM9M10G45,SYS_USE_MMC"
+CONFIG_SYS_PROMPT="U-Boot> "
 # CONFIG_CMD_BDI is not set
 # CONFIG_CMD_IMI is not set
 # CONFIG_CMD_IMLS is not set
 
 
 #define CONFIG_BAUDRATE                        115200
 
-#define CONFIG_SYS_PROMPT      "U-Boot> "
 #define CONFIG_SYS_CBSIZE      256
 #define CONFIG_SYS_MAXARGS     16
 #define CONFIG_SYS_PBSIZE      (CONFIG_SYS_CBSIZE  \