fix: drop premature kernel 8.x, quote WOLFSSL_ROOT, fix regex

- Remove kernel 8.x from BUILD_EXCLUSIVE_KERNEL (doesn't exist yet)
- Quote WOLFSSL_ROOT expansion for paths with spaces
- Add trailing \. to 3.1x regex branch for consistency

Author: MarkAtwood

kernel-src/dkms.conf

@@ -5,7 +5,7 @@ AUTOINSTALL=yes
 BUILT_MODULE_NAME="wolfguard"
 DEST_MODULE_LOCATION="/wolfssl"
 
-MAKE="make -j WOLFSSL_ROOT=${WOLFSSL_ROOT:-/usr/src/wolfssl} module"
+MAKE="make -j WOLFSSL_ROOT='${WOLFSSL_ROOT:-/usr/src/wolfssl}' module"
 
-# requires kernel 3.10 - 8.x, inclusive:
-BUILD_EXCLUSIVE_KERNEL="^(([87654]\.)|(3\.1[0-9]))"
+# requires kernel 3.10 - 7.x, inclusive:
+BUILD_EXCLUSIVE_KERNEL="^(([7654]\.)|(3\.1[0-9]\.))"