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/qemu_arm64_defconfig b/configs/qemu_arm64_defconfig
index 8d5c575..18f3433 100644
--- a/configs/qemu_arm64_defconfig
+++ b/configs/qemu_arm64_defconfig
@@ -22,6 +22,7 @@
 # CONFIG_DISPLAY_CPUINFO is not set
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_PCI_INIT_R=y
+CONFIG_SYS_PBSIZE=532
 CONFIG_CMD_BOOTEFI_SELFTEST=y
 CONFIG_CMD_NVEDIT_EFI=y
 CONFIG_CMD_DFU=y