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/edminiv2_defconfig b/configs/edminiv2_defconfig
index 4987e09..c3293e2 100644
--- a/configs/edminiv2_defconfig
+++ b/configs/edminiv2_defconfig
@@ -25,6 +25,7 @@
 CONFIG_HUSH_PARSER=y
 # CONFIG_AUTO_COMPLETE is not set
 CONFIG_SYS_PROMPT="EDMiniV2> "
+CONFIG_SYS_PBSIZE=1051
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_IDE=y
 CONFIG_CMD_I2C=y