powerpc/pseries: Fix potential memleak in papr_get_attr()

`buf` is allocated in papr_get_attr(), and krealloc() of `buf`
could fail. We need to free the original `buf` in the case of failure.

Fixes: 3c14b73 ("powerpc/pseries: Interface to represent PAPR firmware attributes")
Signed-off-by: Qiheng Lin <linqiheng@huawei.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20221208133449.16284-1-linqiheng@huawei.com

Author: ATRiiX

arch/powerpc/platforms/pseries/papr_platform_attributes.c

@@ -101,10 +101,12 @@ static int papr_get_attr(u64 id, struct energy_scale_attribute *esi)
 		esi_buf_size = ESI_HDR_SIZE + (CURR_MAX_ESI_ATTRS * max_esi_attrs);
 
 		temp_buf = krealloc(buf, esi_buf_size, GFP_KERNEL);
-		if (temp_buf)
+		if (temp_buf) {
 			buf = temp_buf;
-		else
-			return -ENOMEM;
+		} else {
+			ret = -ENOMEM;
+			goto out_buf;
+		}
 
 		goto retry;
 	}