gnu: u-boot-tools: Simplify build.

* gnu/packages/bootloaders.scm (u-boot-tools)[arguments]<#:phases>[build]:
Modify.

gnu/packages/bootloaders.scm

@@ -425,9 +425,7 @@ (define-public u-boot-tools
              (apply invoke "make" "tools_defconfig" make-flags)))
          (replace 'build
            (lambda* (#:key inputs make-flags #:allow-other-keys)
-             (apply invoke "make" "tools-only" make-flags)
-             (apply invoke "make" "envtools" make-flags)
-             (invoke "make" "-C" "tools" "sunxi-spl-image-builder")))
+             (apply invoke "make" "tools-all" make-flags)))
          (replace 'install
            (lambda* (#:key outputs #:allow-other-keys)
              (let* ((out (assoc-ref outputs "out"))