scripts/config: replace hard-coded script name by a dynamic value

The script `config' prints its name in usage() function. It is currently
hard-coded to value `config'. However, the script may be reused under
a different name in contexts other than the Linux Kernel.

Replace the hard-coded value `config' by the name of the script at runtime.
Signed-off-by: Clement Chauplannaz <chauplac@gmail.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

scripts/config

 #!/bin/bash
 # Manipulate options in a .config file from the command line
 
+myname=${0##*/}
+
 # If no prefix forced, use the default CONFIG_
 CONFIG_="${CONFIG_-CONFIG_}"
 
@@ -8,7 +10,7 @@ usage() {
 	cat >&2 <<EOL
 Manipulate options in a .config file from the command line.
 Usage:
-config options command ...
+$myname options command ...
 commands:
 	--enable|-e option   Enable option
 	--disable|-d option  Disable option
@@ -33,14 +35,14 @@ options:
 	--file config-file   .config file to change (default .config)
 	--keep-case|-k       Keep next symbols' case (dont' upper-case it)
 
-config doesn't check the validity of the .config file. This is done at next
+$myname doesn't check the validity of the .config file. This is done at next
 make time.
 
-By default, config will upper-case the given symbol. Use --keep-case to keep
+By default, $myname will upper-case the given symbol. Use --keep-case to keep
 the case of all following symbols unchanged.
 
-config uses 'CONFIG_' as the default symbol prefix. Set the environment
-variable CONFIG_ to the prefix to use. Eg.: CONFIG_="FOO_" config ...
+$myname uses 'CONFIG_' as the default symbol prefix. Set the environment
+variable CONFIG_ to the prefix to use. Eg.: CONFIG_="FOO_" $myname ...
 EOL
 	exit 1
 }