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/r8a77980_condor_defconfig b/configs/r8a77980_condor_defconfig
index a3716dc..17df03c 100644
--- a/configs/r8a77980_condor_defconfig
+++ b/configs/r8a77980_condor_defconfig
@@ -24,6 +24,7 @@
 # CONFIG_BOARD_EARLY_INIT_F is not set
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_MAXARGS=64
+CONFIG_SYS_PBSIZE=2068
 CONFIG_CMD_BOOTZ=y
 CONFIG_CMD_DFU=y
 CONFIG_CMD_GPIO=y