sunxi: Fix Orangepi_mini dtb filename

The Orangepi_mini is different enough from the regular Orangepi that it needs
its own dtb, but when it got added a copy and paste error was made and it
got the same dtb filename, fix this.

While at it also add a short description of both Orangepi boards to the
defconfig files for them.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

configs/Orangepi_defconfig

+# The Orangepi is a development board using the Allwinner A20 SoC, with 1G
+# RAM, microsd slot, HDMI, 1Gbit ethernet, USB wifi, Micro USB (otg), sata,
+# 4 USB A ports, ir receiver and a headphones jack.
+#
+# Also see:
+# http://linux-sunxi.org/Xunlong_Orange_Pi
+# http://www.orangepi.org/
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="AXP209_POWER,SUNXI_GMAC,RGMII,MACPWR=SUNXI_GPH(23),AHCI,USB_EHCI"
 CONFIG_FDTFILE="sun7i-a20-orangepi.dtb"

configs/Orangepi_mini_defconfig

+# The Orangepi mini is a development board using the Allwinner A20 SoC,
+# with 1G RAM, 2 microsd slots (use the top side one for booting), HDMI,
+# 1Gbit ethernet, USB wifi, Micro USB (otg), sata, 2 USB A ports,
+# ir receiver and a headphones jack.
+#
+# Also see:
+# http://linux-sunxi.org/Xunlong_Orange_Pi_Mini
+# http://www.orangepi.org/
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="AXP209_POWER,SUNXI_GMAC,RGMII,MACPWR=SUNXI_GPH(23),AHCI,USB_EHCI"
-CONFIG_FDTFILE="sun7i-a20-orangepi.dtb"
+CONFIG_FDTFILE="sun7i-a20-orangepi-mini.dtb"
 CONFIG_MMC_SUNXI_SLOT_EXTRA=3
 CONFIG_MMC0_CD_PIN="PH10"
 CONFIG_MMC3_CD_PIN="PH11"