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/xilinx_zynqmp_mini_qspi_defconfig b/configs/xilinx_zynqmp_mini_qspi_defconfig
index 00ba942..e2dca7e 100644
--- a/configs/xilinx_zynqmp_mini_qspi_defconfig
+++ b/configs/xilinx_zynqmp_mini_qspi_defconfig
@@ -25,6 +25,7 @@
 # CONFIG_AUTO_COMPLETE is not set
 # CONFIG_SYS_LONGHELP is not set
 CONFIG_SYS_MAXARGS=64
+CONFIG_SYS_PBSIZE=1049
 # CONFIG_CMD_BDI is not set
 # CONFIG_CMD_CONSOLE is not set
 # CONFIG_CMD_BOOTD is not set