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/bcm_ns3_defconfig b/configs/bcm_ns3_defconfig
index a3ada3c..70379d7 100644
--- a/configs/bcm_ns3_defconfig
+++ b/configs/bcm_ns3_defconfig
@@ -25,6 +25,7 @@
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="u-boot> "
 CONFIG_SYS_MAXARGS=64
+CONFIG_SYS_PBSIZE=1049
 # CONFIG_SYS_XTRACE is not set
 CONFIG_CMD_GPT=y
 CONFIG_CMD_GPT_RENAME=y