scripts/get_abi: Fix wrong script file name in the help message

The help message of 'get_abi.pl' is mistakenly saying it's
'abi_book.pl'.  This commit fixes the wrong name in the help message.

Fixes: bbc249f2b8 ("scripts: add an script to parse the ABI files")
Signed-off-by: SeongJae Park <sj@kernel.org>
Link: https://lore.kernel.org/r/20220419121636.290407-1-sj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

scripts/get_abi.pl

@@ -981,11 +981,11 @@ __END__
 
 =head1 NAME
 
-abi_book.pl - parse the Linux ABI files and produce a ReST book.
+get_abi.pl - parse the Linux ABI files and produce a ReST book.
 
 =head1 SYNOPSIS
 
-B<abi_book.pl> [--debug <level>] [--enable-lineno] [--man] [--help]
+B<get_abi.pl> [--debug <level>] [--enable-lineno] [--man] [--help]
 	       [--(no-)rst-source] [--dir=<dir>] [--show-hints]
 	       [--search-string <regex>]
 	       <COMMAND> [<ARGUMENT>]