Convert CONFIG_SYS_PBSIZE to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_PBSIZE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/da850evm_direct_nor_defconfig b/configs/da850evm_direct_nor_defconfig
index b1d84f1..68318dc 100644
--- a/configs/da850evm_direct_nor_defconfig
+++ b/configs/da850evm_direct_nor_defconfig
@@ -29,6 +29,7 @@
 CONFIG_MISC_INIT_R=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="U-Boot > "
+CONFIG_SYS_PBSIZE=1050
 # CONFIG_CMD_BOOTZ is not set
 CONFIG_CMD_IMLS=y
 CONFIG_CRC32_VERIFY=y