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/ls1028ardb_tfa_SECURE_BOOT_defconfig b/configs/ls1028ardb_tfa_SECURE_BOOT_defconfig
index 72625e1..15777f9 100644
--- a/configs/ls1028ardb_tfa_SECURE_BOOT_defconfig
+++ b/configs/ls1028ardb_tfa_SECURE_BOOT_defconfig
@@ -29,6 +29,7 @@
 CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0 earlycon=uart8250,mmio,0x21c0500 ramdisk_size=0x2000000 default_hugepagesz=2m hugepagesz=2m hugepages=256 video=1920x1080-32@60 cma=256M"
 CONFIG_ID_EEPROM=y
 CONFIG_SYS_MAXARGS=64
+CONFIG_SYS_PBSIZE=532
 CONFIG_CMD_GREPENV=y
 CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS=5
 CONFIG_CMD_MEMTEST=y