um: create a proper drivers Kconfig

Merge arch/um/Kconfig.char and arch/um/Kconfig.net into a new
arch/um/drivers/Kconfig.  This fits the way Kconfig files are placed
elsewhere in the kernel tree.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 69fa01a..ea35bf9 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -194,14 +194,12 @@
 
 source "kernel/Kconfig.freezer"
 
-source "arch/um/Kconfig.char"
+source "arch/um/drivers/Kconfig"
 
 source "drivers/Kconfig"
 
 source "net/Kconfig"
 
-source "arch/um/Kconfig.net"
-
 source "fs/Kconfig"
 
 source "security/Kconfig"