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/theadorable-x86-conga-qa3-e3845-pcie-x4_defconfig b/configs/theadorable-x86-conga-qa3-e3845-pcie-x4_defconfig
index 25758b4..daaefba 100644
--- a/configs/theadorable-x86-conga-qa3-e3845-pcie-x4_defconfig
+++ b/configs/theadorable-x86-conga-qa3-e3845-pcie-x4_defconfig
@@ -27,6 +27,7 @@
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_LAST_STAGE_INIT=y
 CONFIG_HUSH_PARSER=y
+CONFIG_SYS_PBSIZE=532
 CONFIG_CMD_CPU=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y