x86/resctrl: Prefer alloc(sizeof(*foo)) idiom in rdt_init_fs_context()

rdt_init_fs_context() sizes a typed allocation using an explicit
sizeof(type) expression, which checkpatch.pl complains about.

Since this code is about to be factored out and made generic, this
is a good opportunity to fix the code to size the allocation based
on the target pointer instead, to reduce the chance of future mis-
maintenance.

Fix it.

No functional change.

Signed-off-by: Dave Martin <[email protected]>
Signed-off-by: James Morse <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Reviewed-by: Fenghua Yu <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Tested-by: Fenghua Yu <[email protected]>
Tested-by: Peter Newman <[email protected]>
Tested-by: Shaopeng Tan <[email protected]>
Tested-by: Amit Singh Tomar <[email protected]> # arm64
Tested-by: Shanker Donthineni <[email protected]> # arm64
Tested-by: Babu Moger <[email protected]>
Tested-by: Tony Luck <[email protected]>
Link: https://lore.kernel.org/[email protected]

Author: Dave Martin

arch/x86/kernel/cpu/resctrl/rdtgroup.c

@@ -2951,7 +2951,7 @@ static int rdt_init_fs_context(struct fs_context *fc)
 {
 	struct rdt_fs_context *ctx;
 
-	ctx = kzalloc(sizeof(struct rdt_fs_context), GFP_KERNEL);
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
 		return -ENOMEM;