ramips: kernel: drop ip_fast_csum() dead loop fix

The issue described in the patch has been fixed by commit
604355e8c4 ("kernel: fix fraglist GRO on linux 6.12")

Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
Link: https://github.com/openwrt/openwrt/pull/22525
Signed-off-by: Robert Marko <robert.marko@sartura.hr>

target/linux/ramips/patches-6.12/325-MIPS-checksum-check-if-data-length-is-zero-in-ip_fas.patch

@@ -1,28 +0,0 @@
-From e34037bd3df9d80c96eda35d346a9220c71a3459 Mon Sep 17 00:00:00 2001
-From: Shiji Yang <yangshiji66@outlook.com>
-Date: Fri, 30 May 2025 19:56:16 +0800
-Subject: [PATCH] MIPS: checksum: check if data length is zero in
- ip_fast_csum()
-
-If ihl equals 0, the nonsensical infinite do while loop will
-eventually access an invalid memory address, which will cause
-the system to halt.
-
-Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
----
- arch/mips/include/asm/checksum.h | 4 ++++
- 1 file changed, 4 insertions(+)
-
---- a/arch/mips/include/asm/checksum.h
-+++ b/arch/mips/include/asm/checksum.h
-@@ -101,6 +101,10 @@ static inline __sum16 ip_fast_csum(const
- 	unsigned int csum;
- 	int carry;
- 
-+	/* ihl should never be zero */
-+	if (unlikely(ihl == 0))
-+		return 0;
-+
- 	csum = word[0];
- 	csum += word[1];
- 	carry = (csum < word[1]);