utils/genrandconfig: increase default target ubifs image size

The new value is calculated based on:
ROOTFS_SIZE = 5G (see commit 3c98eb26db6501a373cc405c80505ba72fde9e96)
BR2_TARGET_ROOTFS_UBIFS_LEBSIZE = 0x1f800

5G / 0x1f800 = 41610

Fixes:
http://autobuild.buildroot.net/results/f72/f72918d63510b170e5da01bfa9c247cf9dcf507f/

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

utils/genrandconfig

@@ -525,6 +525,11 @@ def fixup_config(sysinfo, configfile):
         configlines.remove('BR2_TARGET_ROOTFS_F2FS_SIZE="100M"\n')
         configlines.append('BR2_TARGET_ROOTFS_F2FS_SIZE="%s"\n' % ROOTFS_SIZE)
 
+    if 'BR2_TARGET_ROOTFS_UBIFS=y\n' in configlines and \
+       'BR2_TARGET_ROOTFS_UBIFS_MAXLEBCNT=2048\n' in configlines:
+        configlines.remove('BR2_TARGET_ROOTFS_UBIFS_MAXLEBCNT=2048\n')
+        configlines.append('BR2_TARGET_ROOTFS_UBIFS_MAXLEBCNT=41610\n')
+
     if 'BR2_TARGET_S500_BOOTLOADER=y\n' in configlines and \
        'BR2_TARGET_S500_BOOTLOADER_BOARD=""\n' in configlines:
         configlines.remove('BR2_TARGET_S500_BOOTLOADER=y\n')