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/dalmore_defconfig b/configs/dalmore_defconfig
index 4eec628..fca2ae6 100644
--- a/configs/dalmore_defconfig
+++ b/configs/dalmore_defconfig
@@ -16,6 +16,7 @@
 CONFIG_SYS_STDIO_DEREGISTER=y
 CONFIG_SYS_PROMPT="Tegra114 (Dalmore) # "
 CONFIG_SYS_MAXARGS=64
+CONFIG_SYS_PBSIZE=2086
 # CONFIG_CMD_IMI is not set
 CONFIG_CMD_DFU=y
 CONFIG_CMD_GPIO=y