arm: fix show_data fallout from KERN_CONT changes

The log format printed by show_data is illegible due to printk change
"commit 4bcc595c ("printk: reinstate KERN_CONT for printing
continuation lines")".

[47160.418043] PC: 0xc05fd830:
[47160.418052] d830
[47160.418058]  51a00331
[47160.418064]  41800c11
[47160.418073]  e1a01231
[47160.418079]  e12fff1e
[47160.418088]  e2522001
[47160.418096]  4a000003
[47160.418104]  e4d03001
[47160.418120]  e1330001
[47160.418128] d850
[47160.418136]  1afffffa
[47160.418144]  e2400001
[47160.418149]  13a00000
[47160.418157]  e12fff1e
[47160.418164]  e92d4011
[47160.418171]  e2522004
[47160.418179]  ba00002b
[47160.418188]  e210c003

To fix this, use pr_cont() instead of the printk() to print
continuing lines.

Signed-off-by: Ji Zhang <ji.zhang@mediatek.com>
Signed-off-by: Miles Chen <miles.chen@mediatek.com>