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/teres_i_defconfig b/configs/teres_i_defconfig
index e7de85e..12e91a5 100644
--- a/configs/teres_i_defconfig
+++ b/configs/teres_i_defconfig
@@ -9,6 +9,7 @@
 CONFIG_USB1_VBUS_PIN="PL7"
 CONFIG_I2C0_ENABLE=y
 CONFIG_PREBOOT="setenv usb_pgood_delay 2000; usb start"
+CONFIG_SYS_PBSIZE=1024
 CONFIG_SPL_SYS_I2C_LEGACY=y
 CONFIG_SYS_I2C_MVTWSI=y
 CONFIG_DM_REGULATOR_FIXED=y