arm: convert Cygnus and NSP boards to Kconfig

Convert the bcm958300k and the bcm958622hr boards from "boards.cfg" to Kconfig.

Signed-off-by: Steve Rae <srae@broadcom.com>
diff --git a/configs/bcm958300k_defconfig b/configs/bcm958300k_defconfig
new file mode 100644
index 0000000..066739d
--- /dev/null
+++ b/configs/bcm958300k_defconfig
@@ -0,0 +1,3 @@
+CONFIG_SYS_EXTRA_OPTIONS="SYS_SDRAM_SIZE=0x20000000"
+CONFIG_ARM=y
+CONFIG_TARGET_BCM958300K=y