Improved Linux kernel version identification

src/binwalk/magic/linux

@@ -11,9 +11,9 @@
 # Finds and prints Linux kernel strings in raw Linux kernels (output like uname -a).
 # Commonly found in decompressed embedded kernel binaries.
 0       string      Linux\x20version\x20    Linux kernel version
->14     byte        0                       {invalid}
->14     byte        !0
->>14    string      x                       %.6s
+>14     byte        >0x33                   {invalid}
+>14     byte        <0x32                   {invalid}
+>14     string      x                       %.6s
 
 # Linux ARM compressed kernel image
 # Starts with 8 NOPs, with 0x016F2818 at offset 0x24