[PATCH] uml: update defconfig

Bring defconfig up to date.

Also disable CONFIG_BLK_DEV_UBD_SYNC by default.  By performing synchronous
I/O to the host, it slows things down, only protects against host crashes, and
can make a UML appear to hang while it waits for the host's disk.

Signed-off-by: Jeff Dike <[email protected]>
Cc: Paolo 'Blaisorblade' Giarrusso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: cfd-36