Adjust grep pattern for finding Kconfig symbols
    
    This script detects unknown Kconfig symbols by checking whether the
    Kconfig macros used in the various *.config files have a corresponding
    Kconfig symbol in the tree. Its core test is done with grep().
    
    It turns out that match pattern used in grep() is too broad. For
    instance, it doesn't report CONFIG_ACPI_PROCFS as unknown because there
    is a Kconfig entry for ACPI_PROCFS_POWER in the tree. Make the pattern
    match Kconfig symbols exactly to correct this.
    
    Signed-off-by: Paul Bolle <pebolle@tiscali.nl>