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/omap3_logic_somlv_defconfig b/configs/omap3_logic_somlv_defconfig
index 0b5ffc0..2c5d60d 100644
--- a/configs/omap3_logic_somlv_defconfig
+++ b/configs/omap3_logic_somlv_defconfig
@@ -36,6 +36,7 @@
 # CONFIG_SPL_POWER is not set
 CONFIG_SYS_PROMPT="OMAP Logic # "
 CONFIG_SYS_MAXARGS=64
+CONFIG_SYS_PBSIZE=1054
 # CONFIG_CMD_IMI is not set
 CONFIG_CMD_SPL=y
 CONFIG_CMD_SPL_NAND_OFS=0x240000