ggml-cpu: Support Q5_0 and Q5_1 on s390x (#15486)

* ggml-cpu: initial q5_0 impl for s390x

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-cpu: updated q5_0 code for better performance

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-cpu: use optimised hsum for better performance

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-cpu: introduce q5_1 simd + refactor q5_0

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-cpu: fix incorrect return type vec_hsum

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-cpu: q5_0 incomplete refactor + table_b2b_0 activation

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-cpu: refactor q5_1

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-cpu: q5_1 update loop unroll to 4

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-cpu: update q5_0 unroll to 4

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-cpu: update build-s390x docs

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-cpu: update unused variables q5_0

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* docs: update the last update date

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

---------

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

ggml/src/ggml-cpu/arch-fallback.h

@@ -150,8 +150,6 @@
 #elif defined(__s390x__)
 // quants.c
 #define quantize_row_q8_K_generic quantize_row_q8_K
-#define ggml_vec_dot_q5_0_q8_0_generic ggml_vec_dot_q5_0_q8_0
-#define ggml_vec_dot_q5_1_q8_1_generic ggml_vec_dot_q5_1_q8_1
 #define ggml_vec_dot_tq1_0_q8_K_generic ggml_vec_dot_tq1_0_q8_K
 #define ggml_vec_dot_tq2_0_q8_K_generic ggml_vec_dot_tq2_0_q8_K
 #define ggml_vec_dot_q2_K_q8_K_generic ggml_vec_dot_q2_K_q8_K