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/ls1046aqds_tfa_defconfig b/configs/ls1046aqds_tfa_defconfig
index 6006d5a..881f1f1 100644
--- a/configs/ls1046aqds_tfa_defconfig
+++ b/configs/ls1046aqds_tfa_defconfig
@@ -39,6 +39,7 @@
 CONFIG_ARCH_MISC_INIT=y
 CONFIG_MISC_INIT_R=y
 CONFIG_SYS_MAXARGS=64
+CONFIG_SYS_PBSIZE=532
 CONFIG_CMD_BOOTZ=y
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_GREPENV=y