libbpf: Fixed various checkpatch issues in libbpf.c

Fixed following checkpatch issues:

WARNING: Block comments use a trailing */ on a separate line
+        * other BPF program's BTF object */

WARNING: Possible repeated word: 'be'
+        * name. This is important to be be able to find corresponding BTF

ERROR: switch and case should be at the same indent
+       switch (ext->kcfg.sz) {
+               case 1: *(__u8 *)ext_val = value; break;
+               case 2: *(__u16 *)ext_val = value; break;
+               case 4: *(__u32 *)ext_val = value; break;
+               case 8: *(__u64 *)ext_val = value; break;
+               default:

ERROR: trailing statements should be on next line
+               case 1: *(__u8 *)ext_val = value; break;

ERROR: trailing statements should be on next line
+               case 2: *(__u16 *)ext_val = value; break;

ERROR: trailing statements should be on next line
+               case 4: *(__u32 *)ext_val = value; break;

ERROR: trailing statements should be on next line
+               case 8: *(__u64 *)ext_val = value; break;

ERROR: code indent should use tabs where possible
+                }$

WARNING: please, no spaces at the start of a line
+                }$

WARNING: Block comments use a trailing */ on a separate line
+        * for faster search */

ERROR: code indent should use tabs where possible
+^I^I^I^I^I^I        &ext->kcfg.is_signed);$

WARNING: braces {} are not necessary for single statement blocks
+       if (err) {
+               return err;
+       }

ERROR: code indent should use tabs where possible
+^I^I^I^I        sizeof(*obj->btf_modules), obj->btf_module_cnt + 1);$

Signed-off-by: Kang Minchul <tegongkang@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221113190648.38556-3-tegongkang@gmail.com