riscv: clean up the macro format in each header file

There are many different formats in each header now, such as
_ASM_XXX_H, __ASM_XXX_H, _ASM_RISCV_XXX_H, RISCV_XXX_H, etc., This patch
tries to unify the format by using _ASM_RISCV_XXX_H, because the most
header use it now. This patch also adds the conditional to the headers
if they lost it.

Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

arch/riscv/include/uapi/asm/elf.h

@@ -9,8 +9,8 @@
  * (at your option) any later version.
  */
 
-#ifndef _UAPI_ASM_ELF_H
-#define _UAPI_ASM_ELF_H
+#ifndef _UAPI_ASM_RISCV_ELF_H
+#define _UAPI_ASM_RISCV_ELF_H
 
 #include <asm/ptrace.h>
 
@@ -95,4 +95,4 @@ typedef union __riscv_fp_state elf_fpregset_t;
 #define R_RISCV_32_PCREL	57
 
 
-#endif /* _UAPI_ASM_ELF_H */
+#endif /* _UAPI_ASM_RISCV_ELF_H */