OMAP4: prm: Replace warm reset API with the offset based version

The warm reset function was still using the obsolete API.
Replace it by the new one and move the file to the proper c file.

Change the function names to stick to the file convention as
suggested by Paul Walmsley <paul@pwsan.com>:
prm_xxx -> prminst_xxx

Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>

arch/arm/mach-omap2/prm44xx.h

@@ -755,8 +755,6 @@ extern u32 omap4_prm_set_inst_reg_bits(u32 bits, s16 inst, s16 idx);
 extern u32 omap4_prm_clear_inst_reg_bits(u32 bits, s16 inst, s16 idx);
 extern u32 omap4_prm_read_bits_shift(void __iomem *reg, u32 mask);
 
-extern void omap4_prm_global_warm_sw_reset(void);
-
 # endif
 
 #endif