alpha: regularize the situation with asm/param.h

The only reason why alpha can't do what sparc et.al. are doing
is that include/asm-generic/param.h relies upon the value of HZ
set for userland header in uapi/asm/param.h being 100.

We need that value to define USER_HZ and we need that definition
to outlive the redefinition of HZ kernel-side. And alpha needs
it to be 1024, not 100 like everybody else.

So let's add __USER_HZ to uapi/asm-generic/param.h, defaulting to
100 and used to define HZ. That way include/asm-generic/param.h
can use that thing instead of open-coding it - it won't be affected
by undefining and redefining HZ.

That done, alpha asm/param.h can be removed and uapi/asm/param.h
switched to defining __USER_HZ and EXEC_PAGESIZE and then including
<asm-generic/param.h> - asm/param.h will resolve to uapi/asm/param.h,
which pulls <asm-generic/param.h>, which will do the right thing
both in the kernel and userland contexts.

Reviewed-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Al Viro <[e-mail]>

arch/alpha/include/asm/param.h

···
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_ALPHA_PARAM_H
-#define _ASM_ALPHA_PARAM_H
-
-#include <uapi/asm/param.h>
-
-# undef HZ
-# define HZ		CONFIG_HZ
-# define USER_HZ	1024
-# define CLOCKS_PER_SEC	USER_HZ	/* frequency at which times() counts */
-
-#endif /* _ASM_ALPHA_PARAM_H */

arch/alpha/include/uapi/asm/param.h

···
 #ifndef _UAPI_ASM_ALPHA_PARAM_H
 #define _UAPI_ASM_ALPHA_PARAM_H
 
-#define HZ		1024
-
+#define __USER_HZ	1024
 #define EXEC_PAGESIZE	8192
 
-#ifndef NOGROUP
-#define NOGROUP		(-1)
-#endif
-
-#define MAXHOSTNAMELEN	64	/* max length of hostname */
+#include <asm-generic/param.h>
 
 #endif /* _UAPI_ASM_ALPHA_PARAM_H */

include/asm-generic/param.h

···
 
 # undef HZ
 # define HZ		CONFIG_HZ	/* Internal kernel timer frequency */
-# define USER_HZ	100		/* some user interfaces are */
+# define USER_HZ	__USER_HZ	/* some user interfaces are */
 # define CLOCKS_PER_SEC	(USER_HZ)       /* in "ticks" like times() */
 #endif /* __ASM_GENERIC_PARAM_H */

include/uapi/asm-generic/param.h

···
 #ifndef _UAPI__ASM_GENERIC_PARAM_H
 #define _UAPI__ASM_GENERIC_PARAM_H
 
+#ifndef __USER_HZ
+#define __USER_HZ	100
+#endif
+
 #ifndef HZ
-#define HZ 100
+#define HZ __USER_HZ
 #endif
 
 #ifndef EXEC_PAGESIZE