opencl: add fused rms_norm_mul

[lhez]

This PR adds fused rms_norm_mul following the pattern in #14800.

Qwen2.5-1.5B on Adreno 750

with fusion

model	size	params	backend	ngl	test	t/s
qwen2 1.5B Q4_0	828.59 MiB	1.54 B	OpenCL	99	pp512	252.30 ± 0.44
qwen2 1.5B Q4_0	828.59 MiB	1.54 B	OpenCL	99	tg128	24.10 ± 0.85

without fusion

model	size	params	backend	ngl	test	t/s
qwen2 1.5B Q4_0	828.59 MiB	1.54 B	OpenCL	99	pp512	252.02 ± 0.51
qwen2 1.5B Q4_0	828.59 MiB	1.54 B	OpenCL	99	tg128	22.94 ± 0.76

Qwen2.5-3B on Adreno 750

with fusion

model	size	params	backend	ngl	test	t/s
qwen2 3B Q4_0	1.62 GiB	3.09 B	OpenCL	99	pp512	136.21 ± 0.10
qwen2 3B Q4_0	1.62 GiB	3.09 B	OpenCL	99	tg128	21.41 ± 0.28

without fusion

model	size	params	backend	ngl	test	t/s
qwen2 3B Q4_0	1.62 GiB	3.09 B	OpenCL	99	pp512	135.85 ± 0.13
qwen2 3B Q4_0	1.62 GiB	3.09 B	OpenCL	99	tg128	19.39 ± 2.65

[CISC]

LGTM, but I can't test.

[rmatif]

Thank you! I was thinking about adding this one

LGTM. Results on Adreno 830:

model	size	params	backend	ngl	test	t/s
llama 1B F16	2.30 GiB	1.24 B	OpenCL	99	pp512	170.73 ± 0.16
llama 1B F16	2.30 GiB	1.24 B	OpenCL	99	tg128	22.64 ± 0.05