compiler/riscv64: Rename to make it more explicit

Compiler name was to generic and could lead to misunderstanding
of which compiler to use.
Current setting -march=rv32imac selects works with SiFive provided
compiler only.

To use this with more strict version one should use
-march=rv32imaczicsr in comman line to enable support to enable
required extension that SiFive compiler implies.

compiler/riscv64/pkg.yml → compiler/riscv64-unknown-elf-sifive/pkg.yml

@@ -17,7 +17,7 @@
 # under the License.
 #
 
-pkg.name: compiler/riscv64
+pkg.name: compiler/riscv64-unknown-elf-sifive
 pkg.type: compiler
 pkg.description: Compiler definition for riscv64 gcc compiler.
 pkg.author: "Apache Mynewt <[email protected]>"

hw/bsp/hifive1/bsp.yml

@@ -21,7 +21,7 @@ bsp.name: "HiFive1"
 bsp.url: https://www.sifive.com/boards/hifive1
 bsp.maker: "SiFive"
 bsp.arch: rv32imac
-bsp.compiler: compiler/riscv64
+bsp.compiler: compiler/riscv64-unknown-elf-sifive
 bsp.linkerscript:
     - "hw/bsp/hifive1/hifive1_app.ld"
     - "hw/bsp/hifive1/hifive1.ld"