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/efi-x86_app32_defconfig b/configs/efi-x86_app32_defconfig
index 7a723c1..4ae74db 100644
--- a/configs/efi-x86_app32_defconfig
+++ b/configs/efi-x86_app32_defconfig
@@ -18,6 +18,7 @@
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_LAST_STAGE_INIT=y
 CONFIG_HUSH_PARSER=y
+CONFIG_SYS_PBSIZE=532
 # CONFIG_CMD_BOOTM is not set
 CONFIG_CMD_PART=y
 # CONFIG_CMD_NET is not set