"make clean" after builds of MatrixVision boards would leave stale
files around:
	board/matrix_vision/mvblm7/bootscript.img
	board/matrix_vision/mvsmr/bootscript.img
Fix this.
Signed-off-by: Wolfgang Denk <wd@denx.de>
               $(obj)tools/mkimage         $(obj)tools/mpc86x_clk         \
               $(obj)tools/ncb             $(obj)tools/ubsha1
        @rm -f $(obj)board/cray/L1/{bootscript.c,bootscript.image}        \
+              $(obj)board/matrix_vision/*/bootscript.img                 \
               $(obj)board/netstar/{eeprom,crcek,crcit,*.srec,*.bin}      \
               $(obj)board/trab/trab_fkt   $(obj)board/voiceblue/eeprom   \
               $(obj)board/armltd/{integratorap,integratorcp}/u-boot.lds  \