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/novena_defconfig b/configs/novena_defconfig
index 0a34e99..a75ce58 100644
--- a/configs/novena_defconfig
+++ b/configs/novena_defconfig
@@ -35,6 +35,7 @@
 CONFIG_SPL_I2C=y
 CONFIG_SPL_WATCHDOG=y
 CONFIG_SYS_MAXARGS=32
+CONFIG_SYS_PBSIZE=532
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_EEPROM=y
 CONFIG_SYS_I2C_EEPROM_BUS=2