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/pogo_v4_defconfig b/configs/pogo_v4_defconfig
index fb564b5..ba4245e 100644
--- a/configs/pogo_v4_defconfig
+++ b/configs/pogo_v4_defconfig
@@ -23,6 +23,7 @@
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="Pogo_V4> "
 CONFIG_SYS_MAXARGS=32
+CONFIG_SYS_PBSIZE=1050
 CONFIG_CMD_BOOTZ=y
 # CONFIG_BOOTM_PLAN9 is not set
 # CONFIG_BOOTM_RTEMS is not set